D&D 5E Modifying an Aboleth: How to determine damage output and CR?

[FowlJ]

Any chance you could provide a pg #?

DMG 280

 

[Dausuul]

DMG 249 is intended for estimating areas of effect when running theater of the mind. It's not a balancing tool, and it's better suited to PCs targeting monsters than vice versa. In general, PCs using spells will hit more targets than monsters will using the same spells, simply because there are usually more monsters than PCs on the battlefield! So there are fewer chances to hit a clump of PCs, and the larger number of monsters means they are more likely to have to worry about friendly fire. (Of course, any villain worth his twirly mustache is going to positively chortle at the opportunity to blow away a few of his own minions. But it's still a drawback, tactically speaking.)

Based on my own experience of DMing battlemat combat, I'd probably use a little over 2 as the number of PC targets for vitriolic sphere. Using a 20-foot radius blast, you can pretty reliably nail two PCs without hitting your own troops; once in a while you can get three, but that's less common. You're pretty much never going to get four without wiping out half your own forces.

 

[dave2008]

DMG 280

Thank you!

 

[Quickleaf]

DMG 249 is intended for estimating areas of effect when running theater of the mind. It's not a balancing tool, and it's better suited to PCs targeting monsters than vice versa. In general, PCs using spells will hit more targets than monsters will using the same spells, simply because there are usually more monsters than PCs on the battlefield! So there are fewer chances to hit a clump of PCs, and the larger number of monsters means they are more likely to have to worry about friendly fire. (Of course, any villain worth his twirly mustache is going to positively chortle at the opportunity to blow away a few of his own minions. But it's still a drawback, tactically speaking.)

So you're saying that DMG 249 high-balls the number of targets caught in an area of effect spell/power, and that because of this the sub-text is that 249 is meant for adjudicating a few PCs vs. a large group of monsters?

I can see that.

Sure wish that was explicitly stated in the DMG.

But then I'm back to my original question for monster design purposes...how to adjudicate how many targets are caught in an area of effect for the purposes of DPR estimates and CR estimation.

Based on my own experience of DMing battlemat combat, I'd probably use a little over 2 as the number of PC targets for vitriolic sphere. Using a 20-foot radius blast, you can pretty reliably nail two PCs without hitting your own troops; once in a while you can get three, but that's less common. You're pretty much never going to get four without wiping out half your own forces.

To pin this down a bit more, your "little over 2 PCs" is purely based on your own DM instincts/experience running an average size party, right? No rules references?

And to present it mathematically, you'd be assuming - using the 3 round DPR calculation model - (Round One) 2 targets, (Round Two) 2 targets, (Round Three) 3 targets. So the mathematical average # targets hit would be 2.33 ?

 

[Quickleaf]

So here's my take on the Aboleth Savant, which I'm estimating to be CR 13. There are actually four "versions" of Aboleth Savants with different spell lists, so there may be some variation in CR. The version below has a spell list geared toward conjuration. I may look for further ways to distinguish the four "versions" (Conjurer, Enchanter, Transmuter, and Illusionist - which was a Necromancer in the original Night Below but didn't make sense).

To begin, here's how I reverse calculated the MM Aboleth's CR. According to my numbers it looks more of a CR 9 than 10, but like with a lot of things in 5e, the proof is in the play and it's not worth splitting hairs over.
[SBLOCK]Aboleth (CR 9)
final CR 9 = (8 + 10) / 2

defense CR 8 = 6 (hp 135 +20 =155) + 2 (ac 17 +2 saves)
offense CR 10 = 9 (DPR 60) + 1 (attack +9)

DPR 60 = (39 + 61 + 81) / 3
(1st round) enslave + psychic drain + tail + charm victim’s attack (~2d8+5) = 0 + 10 +15 + 14 = 39
(2nd round) multiattack + psychic drain + tail = 36 + 10 + 15 = 61
(3rd round) multiattack + tailx3 = 36 + 45 = 81[/SBLOCK]

And here's how I calculated the Aboleth Savant's CR 13. You'll notice that I didn't have it use its Enslave ability. In my campaign, by the time the PCs reach the Aboleth Savants they'll likely have completed a ritual granting themselves and their companions immunity to aboleth domination, so in this case the Aboleth Savant's psychic drain is being used on a pre-existing enslaved minion, not a PC.
[SBLOCK]Aboleth Savant, conjurer (CR 13)
final CR 13 = (10 + 16) / 2

defense CR 10 = 9 (hp 170 + 28 =198) + 1 (ac 17 +2 saves)
offense CR 16 = 17 (DPR 110) -1 (attack +9, spell save DC 17)

DPR 110 = (104 + 104 + 123) / 3
(1st round) vitriolic sphere (hits 2 in 20-ft radius) + psychic drain + tail = 75 + 14 + 15 = 104
(2nd round) vitriolic sphere (hits 2 in 20-ft radius) + psychic drain + tail = 75 + 14 + 15 = 104
(3rd round) multiattack + tailx3 + wounded fury (x6) = 36 + 45 + 42 = 123[/SBLOCK]

Upgrades the Aboleth Savant receives over the MM Aboleth:

• Size increased to Huge, HD to 20d12 + 40
• +1 Intelligence
• Spellcasting, 11th level, from any spell list
• Wounded Fury, from the Quaggoth in MM
• Enslave improved with greater frequency, improved range, and harder DC
• Psychic Drain legendary action 4d6 instead of 3d6

Sources:
Night Below by Carl Sargent, 1995
Ecology of the Aboleth by Brandon Grist, DRAGON 131, 1988

Aboleth Savant, The Conjurer
Huge aberration, lawful evil
Armor Class 17 (natural armor)
Hit Points 170 (20d12 + 40)
Speed 10ft., swim 40ft.
STR 21 (+5)
DEX 9 (- 1)
CON 15 (+2)
INT 20 (+5)
WIS 16 (+3)
CHA 18 (+4)
Saving Throws Con +6, Int +8, Wis +7
Skills Arcana +13, History +13, Perception +11
Senses darkvision 120 ft., tremorsense 120 ft., passive Perception 21
Languages Deep Speech, telepathy 120ft.
Challenge 13 (10,000 XP)

Amphibious. The aboleth savant can breathe air and water.
Mucous Cloud. While underwater, the aboleth savant is surrounded by transformative mucus. A creature that touches the aboleth savant or that hits it with a melee attack while within 5 feet of it must make a DC 15 Constitution saving throw. On a failure, the creature is diseased for 1d4 hours. The diseased creature can breathe only underwater.
Probing Telepathy. If a creature communicates telepathically with the aboleth savant, the aboleth learns the creature's greatest desires if the aboleth can see the creature.
Spellcasting (conjuration). The aboleth savant is an 11th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). It has the following spells prepared, requiring no material components:
Cantrips (at-will): acid splash, eldritch blast, mage hand, minor illusion
1st level (4 slots): arms of hadar, detect magic, fog cloud, witch bolt
2nd level (3 slots): darkness, misty step, shatter
3rd level (3 slots): conjure animals, glyph of warding, hunger of hadar
4th level (3 slots): dimension door, evard’s black tentacles, vitriolic sphere
5th level (2 slots): conjure elemental, teleportation circle
6th level (1 slot): arcane gate
Wounded Fury. While it has 40 hit points or fewer, the aboleth savant loses its Spellcasting ability, and instead has advantage on attack rolls. In addition, it deals an extra 7 (2d6) damage to any target it hits with a melee attack.

ACTIONS
Multiattack. The aboleth savant makes three tentacle attacks.
Tentacle. Melee Weapon Attack: +9 to hit, reach 10ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw can be removed by any magic that cures disease. After 1 minute, the diseased creature's skin becomes translucent and slimy, the creature can't regain hit points unless it is underwater, and the disease can be removed only by heal or another disease-curing spell of 6th level or higher. When the creature is outside a body of water, it takes 6 (1d12) acid damage every 10 minutes unless moisture is applied to the skin before 10 minutes have passed.
Tail. Melee Weapon Attack: +9 to hit, reach 10ft. one target. Hit: 15 (3d6 + 5) bludgeoning damage.
Enslave (4/Day). The aboleth savant targets one creature it can see within 60 feet of it. The target must succeed on a DC 17 Wisdom saving throw or be magically charmed by the aboleth until the aboleth dies or until it is on a different plane of existence from the target. The charmed target is under the aboleth's control and can't take reactions, and the aboleth and the target can communicate telepathically with each other over any distance. Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends. No more than once every 24 hours, the target can also repeat the saving throw when it is at least 1 mile away from the aboleth.

LEGENDARY ACTIONS
The aboleth savant can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a tim e and only at the end of another creature's turn . The aboleth savant regains spent legendary actions at the start of its turn.
Detect. The aboleth savant makes a Wisdom (Perception) check.
Tail Swipe. The aboleth savant makes one tail attack.
Psychic Drain (Costs 2 Actions). One creature charmed by the aboleth savant takes 14 (4d6) psychic damage, and the aboleth savant regains hit points equal to the damage the creature takes.

 

[AtomicPope]

OMG! This is brilliant! You just saved me a boat load of time. I'm in the process of starting a campaign this week where the players will face the rebirth of the Aboleth Empire. I really needed this for later tier BBEGs. Granted, I won't be using them for probably 7-8 months but it's a great primer.

I'm going to have to find Carl Sargents Night Below somewhere online. Thanks again!

 

[Quickleaf]

OMG! This is brilliant! You just saved me a boat load of time. I'm in the process of starting a campaign this week where the players will face the rebirth of the Aboleth Empire. I really needed this for later tier BBEGs. Granted, I won't be using them for probably 7-8 months but it's a great primer.

I'm going to have to find Carl Sargents Night Below somewhere online. Thanks again!

Sure, glad you'll get some use from it too.

But, really, it's a simple power boost...I'm not convinced the spellcasting is enough to make the greater aboleth / aboleth savant stand out compared to regular aboleths. I think the next step is to try to incorporate some new lair actions, some of the ideas from DRAGON 131 and perhaps Pathfinder.

 

[dave2008]

Nice variant aboleth, and thank you for sharing.

I do have a question about the CR: Where is the +28 hit points coming from in CR calculation? With the HP at 170 it would be a CR 12 I think.

 

[Quickleaf]

Nice variant aboleth, and thank you for sharing.

I do have a question about the CR: Where is the +28 hit points coming from in CR calculation? With the HP at 170 it would be a CR 12 I think.

You're welcome!

+28 hp is from two uses of Psychic Drain (which I upped to 14 avg. hp instead of 10 like the MM aboleth) over the course of three rounds of combat. 14 + 14 = 28.

You'll notice my calculations for the MM aboleth make the same assumption (only Psychic Drain grants 10 hp in that case, so 10 + 10 = 20).

EDIT: Some legendary actions I'm considering adding...

Phantasmal Force. Cast at-will without components.

Active Domination. Creatures within 60 feet charmed by the aboleth savant's Enslave ability cannot repeat their saving throw versus Enslave when taking damage, unless it is psychic damage. Additionally, if they would be charmed by another creature's spell, they can repeat their save versus Enslave.

 

[dave2008]

You're welcome!

+28 hp is from two uses of Psychic Drain (which I upped to 14 avg. hp instead of 10 like the MM aboleth) over the course of three rounds of combat. 14 + 14 = 28.

You'll notice my calculations for the MM aboleth make the same assumption (only Psychic Drain grants 10 hp in that case, so 10 + 10 = 20).

EDIT: Some legendary actions I'm considering adding...

Phantasmal Force. Cast at-will without components.

Active Domination. Creatures within 60 feet charmed by the aboleth savant's Enslave ability cannot repeat their saving throw versus Enslave when taking damage, unless it is psychic damage. Additionally, if they would be charmed by another creature's spell, they can repeat their save versus Enslave.

Got it. Personally I wouldn't add the extra hit points in the calculation as it requires you to subtract damage (10 hp gain for net 20 damage lost). If you added the HP did you remove the extra damage from legendary attack actions in the attack CR? It didn't seem like you did, but I may have missed it.

I like both your legendary actions; however, I might suggest you limit phantasmal force to 1/round (either simply state 1/round or make it cost 2 actions). As you have it now it could cast 3 in one round and that seems a bit much, but I would have to review the spell again to make sure.

EDIT: I just reviewed your CR calculation. When you up the psychic drain damage/hp recovery to 14 it makes it a more reasonable swap. No real issue with it now.