Need Help with Homebrew Final Boss

[Arctic Wolf]

Finally came up with an outline for each phase of the fight:

After watching the the awe-inspiring, catacylsmic fight between the fallen god of death, Nerull, and the demon prince, Nihilious for the time gem of death. Nihilious tears the gem out of Nerull's broken body and then with a cruel and mocking smirk, he infuses his divine essense in the gem and devours it and finally ending Nerull's life. A sword suddenly appears where the body was. Then Nihilious picks it up and runs it into his hand and it disappears. He then turns to the PCs and thanks them with a maleviolent smile and says that sadly, a fallen god was not enough to really test him and since he now has a divine spark, he wants to cut loose and see how strong his "champions" are and sends them through the first obstacle.

Phase 1) The PCs suddenly feel afflicted with slow that they can't save against and see a bunch of demonic slime (MotP) coming toward them. They have to escape but find a few time wrinkles in there way. The demonic slime will be moving 2 squares per turn but with all the time wrinkles there, it will seem quicker with the the rerolling initiative a lot. They will use Arcana checks to destroy the time wrinkles and I will have radiant damage freeze the demonic slime for one round. (If you think I should throw in some more stuff let me know.)

Phase 2) The PCs face Nihilious in his human form as a spellcaster and must damage him from full hp to half. This will be difficult because he takes a lot of turns per round and can slow the PCs from reaching him.

Phase 3) He turns into his demon form and faces the PCs in melee combat, which will surprise them. This is where the PCs will need to work to control him from doing a lot of damage since melee is his forte. In this stage he will have a more demonic stat block while still having some aspects of his time mastery abilities.

Phase 4) After he reaches 100 hp he instantly teleports away and turns into his human form again. He then tells the PCs (assuming they make it this far) that they will be the first mortals to behold his ultimate ability, Wasteland of Forgotten Blades. When he uses this, the area becomes a field of sand with what looks like an infinite amount of longswords (yes I know I am copying kingdom hearts and fate/night ) and a full moon with a sun are opposite on each side overhead, lighting the area.
The PCs lose their weapons and have to use the swords to defeat him. He will be using the swords too. Each sword is a +6 sword and they use their highest mod to attack. It will be a minor action to pick one up and when they do, they see the entire life of the being whose timeline is stored within (good for RP and just fun in general). Any PCs that die in here are permenantly dead and turn into a blade to keep up with the theme. Their partners will get an extra bonus on rolls and damage with these blades. Finally, after all the fighting, assuming the PCs win, he will either die or admit defeat.

So what do you all think? Sound fun?

 

[Quickleaf]

How do ya like what I did with the triggers now? Also thanks again Quickleaf

You're welcome I really like that field of thousand blades. Never played kingdom hearts so it's new to me!

I have more comments but a quick question first: what level are your PCs now? how far off is this confrontation?

 

[Arctic Wolf]

You're welcome I really like that field of thousand blades. Never played kingdom hearts so it's new to me!

I have more comments but a quick question first: what level are your PCs now? how far off is this confrontation?

Well to be honest, I haven't even started yet since we are finishing another campaign first xD. I know it might be bad to get ahead of myself but I wanna get this done for some reason

 

[Quickleaf]

Well to be honest, I haven't even started yet since we are finishing another campaign first xD. I know it might be bad to get ahead of myself but I wanna get this done for some reason

Fair enough. Here's where I give my usual advice about adapting to the players, prepping to improvise, blah, blah.

Finally came up with an outline for each phase of the fight:

After watching the the awe-inspiring, catacylsmic fight between the fallen god of death, Nerull, and the demon prince, Nihilious for the time gem of death. Nihilious tears the gem out of Nerull's broken body and then with a cruel and mocking smirk, he infuses his divine essense in the gem and devours it and finally ending Nerull's life. A sword suddenly appears where the body was. Then Nihilious picks it up and runs it into his hand and it disappears. He then turns to the PCs and thanks them with a maleviolent smile and says that sadly, a fallen god was not enough to really test him and since he now has a divine spark, he wants to cut loose and see how strong his "champions" are and sends them through the first obstacle.

Look good "on paper." Obviously very conditional on what happens prior.

Phase 1) The PCs suddenly feel afflicted with slow that they can't save against and see a bunch of demonic slime (MotP) coming toward them. They have to escape but find a few time wrinkles in there way. The demonic slime will be moving 2 squares per turn but with all the time wrinkles there, it will seem quicker with the the rerolling initiative a lot. They will use Arcana checks to destroy the time wrinkles and I will have radiant damage freeze the demonic slime for one round. (If you think I should throw in some more stuff let me know.)

You've got a demon prince, thief of time, and you want to send slimed after the PCs? Huh? Also this challenge depends on the epic level PCs running, right? I'm pretty sure this is a Bad Idea.

What's the essence of what you want to have happen in the first phase?

For example, I was expecting the PCs to be thrown into a temporal rift type skill challenge or puzzle/hazard.

Also as a matter of preference, I put non-combat phases in the middle of fights not at the beginning. Generally a boss fight begins with a new session (and takes the entire session). At the start of my game sessions players are chomping at the bit for combat.

Phase 2) The PCs face Nihilious in his human form as a spellcaster and must damage him from full hp to half. This will be difficult because he takes a lot of turns per round and can slow the PCs from reaching him.

What about terrain? If he's primarily an artillery or controller in his spellcaster form (and he's encountered by himself), then go nuts with terrain. I've not run epic games but I've heard a lot of folks talk about the importance of damaging terrain at epic tier.

For example, a field of entropy. Mortals age within it, eventually become weakened (or, preferably, an alternative to weakened, I'll post in a separate thread some homebrew stuff). Terrain crumbles and warps, causing damage which can be mitigated with Acrobatics, Endurance, or Arcana checks. As the fight progresses the terrain fractures into floating isles of earth, and eventually dissolves into nothingness. Time to fly or die!

Phase 3) He turns into his demon form and faces the PCs in melee combat, which will surprise them. This is where the PCs will need to work to control him from doing a lot of damage since melee is his forte. In this stage he will have a more demonic stat block while still having some aspects of his time mastery abilities.

I'm not really feeling the way youre presenting this transformation. It kinda flies in the face of the whole "master of time" theme. But if that's what you want, maybe you could toss out some ideas for what kind of powers his demonic form would have?

From experience, I strongly encourage you to ditch "Variable Resistance" in favor of something else (Demonomicon has alternative suggestions). It sucks to track and slows play. Then again maybe at epic it's no big deal, and with a boss you don't mind a slow fight. Hmm. Your call.

Phase 4) After he reaches 100 hp he instantly teleports away and turns into his human form again. He then tells the PCs (assuming they make it this far) that they will be the first mortals to behold his ultimate ability, Wasteland of Forgotten Blades. When he uses this, the area becomes a field of sand with what looks like an infinite amount of longswords (yes I know I am copying kingdom hearts and fate/night ) and a full moon with a sun are opposite on each side overhead, lighting the area.

I love this! I'm not sure why he's in spellcaster form since isn't the idea that as he weakens his true form is revealed? Which would be a demon right?

The PCs lose their weapons and have to use the swords to defeat him. He will be using the swords too. Each sword is a +6 sword and they use their highest mod to attack. It will be a minor action to pick one up and when they do, they see the entire life of the being whose timeline is stored within (good for RP and just fun in general).

While the scene is very evocative, I don't like this idea for 2 reasons.

(1) Since it hurts implement users it effectively puts melee fighters in the spotlight for no particular reason. You could mitigate this by allowing folks to use the swords as implements. Still ranged attackers would get screwed.

(2) It requires math on the spot. IME/IMO not worth it. You could recalculate everyone's attack/damage values during game prep. Still don't see much point to it.

Also why do they lost their weapons? What's the justification? As 4e characters are extremely weapon/implement dependent I just don't see this working as you've presented it. Instead, what if each sword acts as a terrain power to negate one of Nihilous's spells or negate some terrain effect?

Any PCs that die in here are permenantly dead and turn into a blade to keep up with the theme. Their partners will get an extra bonus on rolls and damage with these blades.

Hey, it's the last fight of the campaign so the PCs are playing for keeps. This seems like a relatively minor way to break the rules. 100 HP gies fast so this wouldn't gimp epic PCs with all their "return from death" powers (they can use those at any time in the fight besides this).

Finally, after all the fighting, assuming the PCs win, he will either die or admit defeat.

Oh he'll die I guarantee it. That's what PCs do with BBEGs.

So what do you all think? Sound fun?

Overall yes, but it needs quite a bit of work.

 

[Arctic Wolf]

Fair enough. Here's where I give my usual advice about adapting to the players, prepping to improvise, blah, blah.


Look good "on paper." Obviously very conditional on what happens prior.


You've got a demon prince, thief of time, and you want to send slimed after the PCs? Huh? Also this challenge depends on the epic level PCs running, right? I'm pretty sure this is a Bad Idea.

What's the essence of what you want to have happen in the first phase?

For example, I was expecting the PCs to be thrown into a temporal rift type skill challenge or puzzle/hazard.

Also as a matter of preference, I put non-combat phases in the middle of fights not at the beginning. Generally a boss fight begins with a new session (and takes the entire session). At the start of my game sessions players are chomping at the bit for combat.


What about terrain? If he's primarily an artillery or controller in his spellcaster form (and he's encountered by himself), then go nuts with terrain. I've not run epic games but I've heard a lot of folks talk about the importance of damaging terrain at epic tier.

For example, a field of entropy. Mortals age within it, eventually become weakened (or, preferably, an alternative to weakened, I'll post in a separate thread some homebrew stuff). Terrain crumbles and warps, causing damage which can be mitigated with Acrobatics, Endurance, or Arcana checks. As the fight progresses the terrain fractures into floating isles of earth, and eventually dissolves into nothingness. Time to fly or die!


I'm not really feeling the way youre presenting this transformation. It kinda flies in the face of the whole "master of time" theme. But if that's what you want, maybe you could toss out some ideas for what kind of powers his demonic form would have?

From experience, I strongly encourage you to ditch "Variable Resistance" in favor of something else (Demonomicon has alternative suggestions). It sucks to track and slows play. Then again maybe at epic it's no big deal, and with a boss you don't mind a slow fight. Hmm. Your call.


I love this! I'm not sure why he's in spellcaster form since isn't the idea that as he weakens his true form is revealed? Which would be a demon right?


While the scene is very evocative, I don't like this idea for 2 reasons.

(1) Since it hurts implement users it effectively puts melee fighters in the spotlight for no particular reason. You could mitigate this by allowing folks to use the swords as implements. Still ranged attackers would get screwed.

(2) It requires math on the spot. IME/IMO not worth it. You could recalculate everyone's attack/damage values during game prep. Still don't see much point to it.

Also why do they lost their weapons? What's the justification? As 4e characters are extremely weapon/implement dependent I just don't see this working as you've presented it. Instead, what if each sword acts as a terrain power to negate one of Nihilous's spells or negate some terrain effect?


Hey, it's the last fight of the campaign so the PCs are playing for keeps. This seems like a relatively minor way to break the rules. 100 HP gies fast so this wouldn't gimp epic PCs with all their "return from death" powers (they can use those at any time in the fight besides this).


Oh he'll die I guarantee it. That's what PCs do with BBEGs.


Overall yes, but it needs quite a bit of work.

Oh yea trust me I'm also prepping to improvise if things turn out differently then planned.

True, I might have some fun prior to the fight, if it happens like that. (once this is done I'm going to write up some moves for Nerull heh )

Yeah, I admit that isn't the best "puzzle/skill check" phase. Below I will write down what I might change it to next.

You gave me an idea to have a time field, but going in reverse time so if the PCs lose they will be erased from history and only known to Nihilious since he will have their *timeline* in his blade.

I think I will start him in his demon lord form first so that way we know that when he turns into his human form he is weakened. How does that sound? I think I will combine the Wasteland stage with his human form so that will be phase 3.

I like the scene also and true. I think I will do it that if they pick up a blade, they get a boon/debuff that lasts one round to make it interesting and give them some random information. I will prepare about 15 different *people* and that they will be able to gain some history from and even Nerull. I might have them roll a d20 to determine which person they get.

Yep, I plan to have it that in the phase 3 no revive items can work so it is for keeps.

Hey, you never know. The PCs might spare him for some reason lol.

So this is what the new phases will be:

Phase 1 Demon Form spell caster fight

Phase 2 Will turn his Time Flashes Before Your Eyes ability into an alternative phase where there is no combat (maybe) but each person experiences it differently. I am thinking that they are automatically sent back in time to a point to where something tramatic happened to cause them to become an adventurer. They have to choose either to reshape the events or let them happen as is. They have to face their *alternate time self* to see if this happens or not which can lead to an outcome. Sound good?

Phase 3 After managing to avoid changing their future, the PCs awaken to find Nihilious in his human form and he then uses his Wasteland of Forgotten Blades. This actually does sound a lot better then what I had before lol. Anything else I should add?

 

[Quickleaf]

You gave me an idea to have a time field, but going in reverse time so if the PCs lose they will be erased from history and only known to Nihilious since he will have their *timeline* in his blade.

I would play around with this idea of a timeline-storing blade. Maybe write it up as a quasi-intelligent weapon which allows Nihilous to summon temporal phantoms of defeated heroes. But once he's bloodied the phantoms can be influenced to aid the PCs.

I think I will start him in his demon lord form first so that way we know that when he turns into his human form he is weakened. How does that sound? I think I will combine the Wasteland stage with his human form so that will be phase 3.

From a story standpoint, the idea of evil's true form further being revealed as the fight wears on makes more sense to me.

I like the scene also and true. I think I will do it that if they pick up a blade, they get a boon/debuff that lasts one round to make it interesting and give them some random information. I will prepare about 15 different *people* and that they will be able to gain some history from and even Nerull. I might have them roll a d20 to determine which person they get.

That sounds interesting, and a good thing to foreshadow early on in yor campaign.

Phase 2 Will turn his Time Flashes Before Your Eyes ability into an alternative phase where there is no combat (maybe) but each person experiences it differently. I am thinking that they are automatically sent back in time to a point to where something tramatic happened to cause them to become an adventurer. They have to choose either to reshape the events or let them happen as is. They have to face their *alternate time self* to see if this happens or not which can lead to an outcome. Sound good?

Is what you're going for a choice between changing something awful (but never becoming an adventurer?) or accepting what happened as necessary for their growth into the person they are? I don't see any players taking option #1 if it means taking them out of the fight.

Also this runs into the split party problem, where players get bored waiting for their turn to come up as they don't have a role to play during each others turns.

I think you can take the spirit of what you're going for and keep it inclusive. Here's where not having started your game yet could work in your favor. Keep notes on contentious issues the party faces, where there's inter-party conflict. Then send the PCs as a group back to a couple of these situations (equal to # of PCs) to resolve as they see fit...albeit with hindsight of what the initial decision's outcome was.

Trick is each situation is keyed to a particular PC (the one with the most emotional tie? or the one who made the initial decision? or better yet the one who felt most disatisfied with the initial decision). An "evil" outcome Favoring the keyed PC could Dominate them temporarily or allow Nihilous to steal some of their power or impose a save penalty on them vs Nihilous attacks. OTOH a "wise" outcome should give the party some kind of group benefit.

Phase 3 After managing to avoid changing their future, the PCs awaken to find Nihilious in his human form and he then uses his Wasteland of Forgotten Blades. This actually does sound a lot better then what I had before lol. Anything else I should add?

If the "no returning from death" will be in effect for a third of the fight, maybe provide subtle foreshadowing that it's coming.

Overall looks good Happy gaming!

 

[Arctic Wolf]

I would play around with this idea of a timeline-storing blade. Maybe write it up as a quasi-intelligent weapon which allows Nihilous to summon temporal phantoms of defeated heroes. But once he's bloodied the phantoms can be influenced to aid the PCs.


From a story standpoint, the idea of evil's true form further being revealed as the fight wears on makes more sense to me.

That sounds interesting, and a good thing to foreshadow early on in yor campaign.


Is what you're going for a choice between changing something awful (but never becoming an adventurer?) or accepting what happened as necessary for their growth into the person they are? I don't see any players taking option #1 if it means taking them out of the fight.

Also this runs into the split party problem, where players get bored waiting for their turn to come up as they don't have a role to play during each others turns.

I think you can take the spirit of what you're going for and keep it inclusive. Here's where not having started your game yet could work in your favor. Keep notes on contentious issues the party faces, where there's inter-party conflict. Then send the PCs as a group back to a couple of these situations (equal to # of PCs) to resolve as they see fit...albeit with hindsight of what the initial decision's outcome was.

Trick is each situation is keyed to a particular PC (the one with the most emotional tie? or the one who made the initial decision? or better yet the one who felt most disatisfied with the initial decision). An "evil" outcome Favoring the keyed PC could Dominate them temporarily or allow Nihilous to steal some of their power or impose a save penalty on them vs Nihilous attacks. OTOH a "wise" outcome should give the party some kind of group benefit.


If the "no returning from death" will be in effect for a third of the fight, maybe provide subtle foreshadowing that it's coming.

Overall looks good Happy gaming!

What do you mean as defeated heroes? Like past champions he has toyed around with as well who have fallen to him? I might be able to make a weapon but would the PCs use it? Do you think I should have it that Nihilious is the one who gave the enemies these gems and is just having fun with the PCs?

Hmm, so now comes the dilemma of making his demon form moves. I think the last thing I'll consider adding to him in general is a no action where he gains 1 action point if anyone dies. This should be fun

True, I will have to make things truely controversial and make sure they all have different stances. I was going to make the campaign pretty dark and seem like a cold world so it might work.

I think I will have Nihilious always give them a slight phrase or something really subtle that will hint at the final fight. I will most likely make another thread laying out my basic campaign but I will leave Nihilious for this thread.

 

[Arctic Wolf]

Stage 1

General Nihail Herald Obyrin​

Level 35 Solo Soldier​

Medium natural humanoid (demon, human)​

XP 235,000​

HP 500; Bloodied 250

AC 49; Fortitude 48; Reflex 48; Will 49​

Speed 8, phasing 8, jump 8​

Immune sleep, charm, disease, poison; Resist 20 necrotic​

Saving Throws +5; Action Points 2​

Initiative +46, Perception +35, Darkvision, Truesight 20​

Traits

Boon of Time
Nihilious can spend action points regardless of whose turn it is as an immediate interrupt. In addition, Nihilious does not grant combat advantage when he is being flanked.

Master of Time
At the start of combat, Nihilious takes initiative checks at 45/30/15. He takes a turn on both initiative counts and Nihilious' ability to take immidiate actions refreshes.

Threatening Reach Aura 5

Nihail can make opportunity attacks against enemies within 5 squares.​

Standard Actions​

One-Thousand Spears of Corroding Time (necrotic) • Recharge 6
Attack: Burst 20 (All Creatures in Burst); +40 vs. Fortitude
Hit: 7d10 + 13 necrotic damage and all targets lose all buffs. In addition, they do not benefit from resistance and immunities to effects and damage (save ends). Until this effect fades, the target looks like an older version of themself.

m Time-Stealing Blade (necrotic) • At-Will​

Attack: Reach 5 (One Creature); +40 vs. Fortitude
Hit: 5d10 + 13 necrotic damage and the target is slowed and takes a -2 penalty to attack rolls (save ends both). Nihail can take an additional movement action after this attack.

r Bolt of Increased Time (necrotic) • At-Will​

Attack: Range 10 (One Creature); +40 vs. Fortitude
Hit: 5d10 + 13 necrotic damage and the target is slowed and takes a -2 penalty to attack rolls (save ends both).

C Temporal Disjunction • At-Will​

Attack: Burst 10 (All Creatures in Burst); +40 vs. Fortitude
Hit: 4d10 + 13 necrotic damage and the target takes a -2 penalty to attack rolls, saving throws, and foritude defense (save ends). Until this effect fades, the target looks like an older version of themself.

Move Actions​

Alacritous Stride • Recharge 5 6​

Effect: Nihail can move three times his speed and make a basic melee attack against each target but not the same one. This movement does not provoke opportunity attacks.

Minor Actions​

Rewind Time (arcane) • At-Will 1/round​

Attack: Range 5 (One zone or area effect within range); +40 vs. Any
Effect: Nihilious dispells one zone or area effect.

Blade-Strike • At-Will​

Attack: Melee 1 or Reach 5 (One Creature); +40 vs. AC
Hit: 4d10 + 13 damage.

Chained Time-Blades • At-Will​

Attack: Burst 5 (One Creatures in Burst); +40 vs. Fortitude
Hit: 4d10 + 15 necrotic damage and the target is slowed and takes a -2 penalty to attack rolls (save ends both).

Ageing Ray • At-Will​

Attack: Range 10 (One Creature); +40 vs. Fortitude
Hit: The target takes a -2 penalty to attack rolls (save ends). Until this effect fades, the target looks like an older version of themself.

Triggered Actions​

Skin of Accelating Time • At-Will 2/round
Trigger: Nihail is subject to an effect.
Effect (Immediate Interrupt): Nihilious is no longer subject to that effect.

Time Skip • At-Will 2/round but once per each target​

Trigger: The enemy makes a saving throw against an effect caused by Nihail.
Effect (Immediate Interrupt): The enemy automatically fails the saving throw.

Time's Reward • At-Will​

Trigger: Nihail reduces a target to zero hit points or fewer.
EffectNo Action): Nihilious gains 1 action point.

Skills

Acrobatics +33, Arcana +32, Athletics +35, Bluff +33, Diplomacy +33, Endurance +33, History +32, Insight +32, Intimidate +33, Religion +32

Str 36 (+30) Dex 33 (+28) Wis 30 (+27) Con 33 (+28) Int 30 (+27) Cha 33 (+28)​

Alignment unaligned　　Languages Abyssal, Supernal, Telepathy 20​

Equipment staff implement​

 

[Arctic Wolf]

Stage 3

Nihilious, Demon Prince of Time​

Level 35 Solo Controller​

Medium elemental humanoid (demon, human)​

XP 235,000​

HP 500; Bloodied 250

AC 46; Fortitude 46; Reflex 50; Will 52

Speed 8, teleport 8, phasing 8

Saving Throws +5; Action Points 2

Initiative +44, Perception +35, Darkvision, Truesight 20

Traits

Time's Erosion
All resistances and immunities to damage and effects are ignored while inside this aura even if Nihilious is conscious or not. All effects that bring a character back to life do not work.

Boon of Time
Nihilious can spend action points regardless of whose turn it is as an immediate interrupt. In addition, Nihilious does not grant combat advantage when he is being flanked.

Master of Time
At the start of combat, Nihilious takes initiative checks at 45/30/15. He takes a turn on both initiative counts and Nihilious' ability to take immidiate actions refreshes.

Standard Actions

R Sphere of Ultimate Destruction (necrotic) •
Recharge target is bloodied by Nihilious
Attack: Range 10 (One Creature); +40 vs. Fortitude
Hit: 8d10 + 11 necrotic damage and the target cannot benefit from healing surges (save ends). If this attack kills the target, Nihilious gains combat advantage against the party for the rest of the encounter. Until this effect fades, the target looks like an older version of themself.

m Time-Stealing Strike (necrotic) • At-Will​

Attack: Melee 1 (One Creature); +40 vs. Fortitude
Hit: 5d10 + 13 necrotic damage and the target is slowed and takes a -2 penalty to attack rolls (save ends both).

r Spear of Corroding Time (necrotic) • At-Will​

Attack: Range 10 (One Creature); +40 vs. Fortitude
Hit: 5d10 + 13 necrotic damage and the target is restrained until the end of their next turn. Until this effect fades, the target looks like an older version of themself.

C Wrinkle in Time • At-Will​

Attack: Close Burst 10 (All Creatures in Burst); +38 vs. Will
Effect: Nihilious teleports his speed away and teleports an enemy within the burst to his former position. All adjacent enemies then makes a basic attack toward that target. .

Timeline Blade Empowerment • At-Will​

Requirements: Needs to be holding a Timeline Blade.
Effect: Gains a standard action power based on the blade he picks up and places in his staff.

Minor Actions​

C Time Rip (necrotic) • At-Will 1/round
Attack: Close Burst 20 (All Creatures in Burst) +38 vs. Reflexes
Effect: 4d8 + 12 nectoric damage and the target is slowed and takes a -2 penalty to attack rolls (save ends both).

Rewind Time(arcane) • At-Will 1/round​

Attack: Range 5 (One zone or area effect within range); +39 vs. Any
Effect: Nihilious dispells one zone or area effect.

Withering Existence • At-Will​

Attack: Range 10 (One Creature); +40 vs. Fortitude
Hit: The target takes 10 ongoing necrotic damage (save ends). Each failed saving throw will double the ongoing damage.

Obyrith's Curse • Recharge 5 6​

Attack: Range 10 (One Creature); +38 vs. Will
Hit: The target takes a -2 penalty to saving throws for the rest of the encounter. This effect can stack.

Triggered Actions​

Skin of Accelating Time • At-Will 2/round​

Trigger: Nihilious is subject to an effect.
Effect (Immediate Interrupt): Nihilious is no longer subject to that effect.

Time Stop • At-Will 2/round​

Trigger: A slowed enemy attacks Nihlious.
Effect (Immediate Interrupt): The enemy's turn is now over and they are no longer slowed.

Time's Reward • At-Will​

Trigger: Nihilious reduces an enemy to zero hit points or fewer.
Effect (No Action): Nihilious gains 1 action point.

Skills ​

Acrobatics +32, Arcana +33, Bluff +33, Diplomacy +33, Endurance +30, History +33, Insight +32, Intimidate +33, Nature +32, Religion +33, Streetwise +33

Str 30 (+27) Dex 30 (+27) Wis 30 (+27) Con 27 (+25) Int 33 (+28) Cha 33 (+28)​

Alignment unaligned　　Languages Abyssal, Supernal, Telepathy 20​

 

[Quickleaf]

Looks good! Though I do have some feedback.

Is 1,000 HP (500 + 500) a little low for a solo epic boss? I thought the formula of about 4 or 5x (24 +8/level) still was being used?

I don't like the triggered action Time Skip because it auto shuts down a player's save. Sure he's an epic boss, but IMHO this adds nothing and feels like a cheap shot at the players. Plus it's another thing for you to track. Would the concept you're going for suffer if you swapped that with something else or just got rid of it?

What is the penalty Temporal Disjunction imposes? For ease of tracking i suggest -2, and to make Ageing Ray also -2 instead of -3. It seems like an insignificant change, but with all the status effects flying around in a boss fight, you'll want any simplification you can get.

Since Time's Erosion is active for what appears to be half the battle (ie. 500 HP), I'd recommend some sort of grace period for the players. Say a round during which they realize that restorative magic is failing; this way they can buff themselves or strategize a way to keep themselves alive. It could be as simple as narrating the preceding stage of combat with foreshadowing.

A thought about the rechargeable powers, particularly Sphere of Ultimate Destruction. Recharge X powers make fights more swingy and add a layer of complexity for the the DM to keep track of. That can be fine for most fights, but probably isn't what you want in a boss fight. I suggest coming up with an alternate recharge mechanic, e.g. when an enemy is bloodied by Nihilous. The good thing about more "organic" recharge mechanics is that they help you think about the developing story of the fight.

For the Timeline Blade Empowerment, you could look to the beholder eye tyrant's rays as a guideline.

Time Rip doesn't gave an attack roll. It needs one. However, since Time Stop only works against slowed enemies, consider carefully what defense Time Rip targets, since PCs with a weak defense in that department are more likely to have their actions shut down by Time Stop.

Actually, I'm not sure I like Time Stop's mechanic. Let me think on it a bit.