Because it amuses me, I'm going to run your BBEG through
D&D 5E - Ridiculously Simple Monster Building
The Core is 1 MBP/8 HP, 1 per AC, 1 per Attack stat bonus, 3 per at-will damage and 1 per one-shot damage.
Extras are 1 per save, 1+legendary resist count
HP: 18.13 MBP
AC: 10 MBP
Attack stat bonus: 12 MBP
Resists: Moderate (+25%) (+4.5)
Regeneration: ~30 HP (4.7, after resist multiplier)
Legendary resists: 4 MBP
Good saves (I assume 4?): 4 MBP
At-will action damage: 45 (15 MBP)
Legendary: using melee, another 45 (15 MBP)
Total: 87.3 MBP.
CR is 87.3-14 over 4=18
Add in tenser's precast is +13*6=+26 MBP, which boosts you to about CR 20.
You'll get a bit of boost from Foresight.
...
Encounter budget. A lazy and pretty damn good way to balance encounter is to add up CR with a bit of a fudge factor for level 10+ and 20+ and +1 per monster.
Water elemental Myrmidon is CR 7
Lampad is CR 3
Cambion is CR 5
Mind Flayer is CR 7
Alias is CR 20
For encounter building points, where CR 1 to 10 is worth 1 per CR, CR 11 to 20 is worth 2, and CR 20+ is worth 4, this adds up to:
Total of 57.
The PCs total encounter budget is 17*4 = 68
At 83% of the player's budget, this should be a hard fight.
Dragonborn Zealot Barbarian- Belt of Storm Giant Strength, Volt Edge(+3 Greatsword and deals 2d6 Lightning damage as well, don't really know how these items got approved by the DM) and nothing else of interest aside from some Boots of Striding and Springing(he joined later)
Aasimar Paladin- +3 Greatsword, Demon Armor and a Ring of Protection.
The bloody Ki-Rin- True Polymorph scroll another DM randomly rolled turned him into the literal stat block-https://5e.tools/bestiary/kirin-vgm.html
Elf Wizard- Robe of the Archmagi, Staff of Defence, Ring of Invisibility, Boots of Elvenkind, Bag of Holding, Master's Amulet, and a spellbook the size of a small library, as well as WAY too many scrolls.
Machina-Shield Guardian with a cloak of displacement.
As far as the OTT items go, I've stepped in to DM from level 13, since the DM and a player had an argument over the magic items, and left. I picked it up since my friends still wanted to play(kind of wanted to do a high level one, but didn't really know what I was getting into). They are still in the Hells anyway.
What do you think of an adaptive ability? More uses of the same spells may build up an immunity, like a Bacteria with Antibiotics. Simply attacking won't work after a while.
Thank you though, for the detail and effort you've put into this.
Ok, here is the part that did it.
Ki-Rin isn't all that bad, but at as CR 12 monster isn't actually going to steal the show against level 13 PCs.
But that barbarian is way-over powered for CR 13.
Demon Armor is junk. +3 greatsword is strong, not as strong as +3 with 2d6 damage. Storm Giant belt is really strong.
Robe of the Archmagi, Staff of Defence, and a Shield Guardian are also big. 7 extra CR for the party.
That barbarian's damage output is easily doubled by the stuff given to him. Paladins are strong in single-encounter days, especially against undead and fiends.
Call the barbarian closer to 25 EBP, and round everyone else up to 21, adding in 8 for the shield guardian, for a total budget of 95 EBP. Let's round up to 100.
68/100 is still past deadly, but deadly in 5e just means "with bad rolls someone dies".
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Start pushing them with multiple encounters.
Standard budgets look something like this:
50 EBP - deadly -- 4 scene building points (50% of PC budget)
40 EBP - hard -- 3 scene building points (40% of PC budget)
30 EBP - medium -- 2 scene building points (30% of PC budget)
20 EBP - easy -- 1 scene building points (20% of PC budget)
We can extend this with +1 SBP for every 10 EBP on top of deadly if we want (10% of the player's encounter budget, which happens to be 100 here).
Remember, "deadly" isn't "one fight for a day deadly". "deadly" means "in a standard adventuring day, the players could lose a PC if they roll poorly".
Similar to encounters, scenes have a budget range:
Easy Scene: 4
Medium Scene: 6
Hard Scene: 8
Deadly scene: 10
We then have Chapter Points ("adventuring day"), where Easy Scene is 1, Medium is 2, Hard is 3, and Deadly is 4.
Easy day: 4
Medium day: 6
Hard day: 8
Deadly day: 10
(You may notice a pattern. Each tier attempts to reflect that clumping stuff is more dangerous than spreading things out. We could use a power curve, but a simple (X+1) resources for (X) cost does a decent job at emulating a power curve if X remains in the 1-4 range; easy medium hard deadly.)
Again, "deadly" doesn't mean "PCs have an even chance of losing" but rather "non-zero chance a PC dies".
Let us build a deadly chapter. We give ourselves 10 Chapter Points.
For Scenes, we'll have 1 Deadly (boss, 4), 1 easy (1), 1 medium (2), 1 hard (3).
For order, how about Easy, Hard, Medium, Deadly -- not pure rising action, there is a lull before the storm.
Our goal? The PCs give up and run away before fighting the boss, or fight the boss and are really scared by it, because they are out of HD, low on spells, and drained.
Easy has 4 SBP, so 2 medium encounters (30 EBP each)
Hard has 8 SBP, so 2 deadly encounters (50 EBP each)
Medium has 6 SBP, so a deadly and two easy encounters (50 EBP and two 20 EBP)
Deadly has 10 SBP, so 1 deadly encounter (4) and one deadly++ (6) encounter (50 and 70 EBP)
In terms of CR, 20 EBP is a CR 15 monster, 25 EBP is one CR 17 monster, 40 EBP is a CR 22 monster, 60 EBP is a CR 27 monster. But usually you'll want to break it down into multiple smaller monsters.
The boss above is a CR 20 creature (or so), which is 31 EBP -- a medium encounter in itself against your party. Stacked with those allies, you'd expect the fight to be challenging -- and it was, they probably burned resources and it took 4 rounds.
Throw that fight against PCs who have pushed through anything like the above budget and they'll be crying.
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Ok, we'll get rid of PC "superscaling" from their cool items. They are back to 74 EBP (sum of CRs and levels, where levels/CR over 10 count double, +1 per creature).
This was a 57 EBP fight, 75% of budget, so 6.5 Scene points. Beyond deadly!
But, a 6.5 point scene all by itself is just a medium scene (6 points).
A chapter with only one medium scene is trivial, easier than easy.
Your PCs roflstomped it.
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Now, I find it hard to
narratively justify the above kind of grind. Which is why I advocate for switching to gritty rests - overnight is a short rest, a week's vacation is a long rest.
Justifying each "scene" being a day, and the lack of an opportunity to have a week's rest over the "chapter".
It means that a dungeon ends up using a scene's budget, not a chapter's budget, but you have plenty of room for that if you don't want the dungeon to be crazy.
With this, you have the protagonist -- the BBEG -- have a plan on the scale of 5-30 days. Players who take a long rest are likely to fail to stop the plan, and the BBEG wraps it up and moves on. Better luck next time. (the BBEG is the protagonist; the players are reacting. This makes sure that you, as a DM, aren't railroading player action. They are free to let the BBEG complete their plots, and you should make that an interesting result!)
For a 5 day plan, that is 1 chapter.
For a 15 day plan, that is 2 chapters.
For a 25 day plan, that is 3 chapters.
etc.
An X chapter adventure should take about 10X-5 days for the bad guy to complete their plans.
Now build a trail of breadcrumbs for the PCs to follow, where each chapter has something that the PCs don't want happen to the world that is blatant and obvious, and investigating it (or stopping it) would lead to the next chapter.
For extra fun, have multiple BBEG each with their own plots. Each plot has a doom (a goal), and chapters.
Chapters have a
portent (public information that the chapter has started; orcs march on a town, graveyard corpses are dug up, dark riders are searching for someone). Then roll 2d10 for how long for the bad guy's to finish their task. At the end, there is a consequence if the PCs don't interfere. If the PCs interfere and stop it, the next chapter kicks off in 2d10 days, if they don't in 1d10 days.
As a sample:
Plot 1: Vizer usurping kingdom. 3 chapters.
- Chapter 1: The Princess (princess's life is threatened)
- Chapter 2: Paying Debts (Plot 4 chapter 1, vizer funds the coup by paying off a bank with a mine)
- Chapter 3: Assassination (Vizer kills king and replaces him)
Plot 2: Necromancer kills entire City to become a Lich. 5 chapters.
- Chapter 1: Uneasy lies the dead (graveyard produces undead, causing problems)
- Chapter 2: The Stolen Cup (an artifact is stolen from the cathedral)
- Chapter 3: Sleepwalkers (people start doing horrible things in their sleep)
- Chapter 4: Inquisition (a possessed archbishop starts a massive purge)
- Chapter 5: Ascension (necromancer sacrifices city for eternal life)
Plot 3: Dragon cult hatch Tiamat and Bahamut's egg, starts a new Dragon empire. 7 chapters.
- Chapter 1: An Archeological Expedition (scholar finds ancient tomb)
- Chapter 2: A Trade Disruption means what? (kobold dragon cultists shut down a trade route)
- Chapter 3: Lost and Found (plot 4, chapter 2) (something is found in the mines)
- Chapter 4: The Stars Align (an astrological event occurs, leading to outpouring of chaotic magic and a problem)
- Chapter 5: A Cold Dish (dragonborn mercenaries are brought in, as part of Plot 2.4 or in response to 1.3 or 4.5).
- Chapter 6: Wages of Death (Necromantic energy harvested for the ritual)
- Chapter 7: All Good Things (Mortal rulership is overthrown by an immortal god-dragon)
Plot 4: Bank reopens ancient mine in exchange for kingdom's debt, delves too deep. 4 chapters (+1 delay)
- Chapter 1: Paying debts (Plot 1, chapter 2)
- Chapter 2: Lost and Found (Plot 3, chapter 3)
- Chapter 3: Riches untold (A rich vein is found)
- Chapter 4: Drums in the deep (Something is awoken in the deep, and if not sealed comes to the surface)
Lacking PC intervention, these plots advance at 1 every 3d10 days (call it 15), so we have (approximately).
45 days from 0 the Vizer overthrows the King.
60 days from 0 an ancient mine spews forth monsters from the deep.
75 days from 0 the entire Capital City is killed.
105 days from 0 a Dragon Empire is reborn.
At 19 chapters over 105 days, that is 5.5 days/chapter. PCs are expected to spend ~10 days clearing a chapter (including resting), and doing so delays the total plots by 5 days; so over 10 chapters they buy enough time to complete another chapter. So the PCs have the time budget to stop about 11/19 of the above plot chapters. So the players will have plenty of plots to follow or ignore. When things happen (like the king is replaced), there will have been plenty of foreshadowing and the PCs will have chosen to not interfere.
If the PCs are slower, no problem, the world spins. If they are faster, also no problem!
Now we return to the D&D assumption that
endurance matters as much as
power, and that attrition of resources is expensive. Not because players are like "if I don't rest I'll die", but rather "if I rest, we'll lose". That pressure on the PCs, that there is more to do than they have time to do, ensures that massive alpha-strikes aren't free.