D&D 5E Help me peg the CR for this villain

[Boarstorm]

In my current campaign, the PCs are storming an ancient Yuan-ti temple. The villain is a Yuan-Ti abomination who also happens to have the spellcasting ability of an 11th level fey pact Warlock. I've tentatively pegged his CR at 8, but I think I may be lowballing it. What do you guys think?

Updated:
http://www.enworld.org/forum/5emonsters/showentry.php?e=41

 

[Boarstorm]

In retrospect, this probably belongs in the homebrew forum. If any mods would like to move it, I would be obliged.

 

[Jack99]

9 or 10.

 

[Boarstorm]

What's your thinking, [MENTION=53135]Jack99[/MENTION]? Based on damage output or versatility or ...?

 

[Jack99]

Not sure why most of my post was eaten. Anyway, if you compare it to a Gynosphinx, it seems close enough to be similar, although the sphinx has legendary actions, so hence 1-2 CRs lower.

 

[Quickleaf]

In my current campaign, the PCs are storming an ancient Yuan-ti temple. The villain is a Yuan-Ti abomination who also happens to have the spellcasting ability of an 11th level fey pact Warlock. I've tentatively pegged his CR at 8, but I think I may be lowballing it. What do you guys think?

Updated:
http://www.enworld.org/forum/5emonsters/showentry.php?e=41

I think 9 or 10 is probably a safe bet.

However, one of the things [MENTION=84774]surfarcher[/MENTION]'s dissection of monster design revealed is that two 11th level spellcasters could have very different CRs. The CR is based on how many of their spells known are offensive - its a damage output calculation. So without knowing the yuan-ti's spell load out, we can only make rough guesses.

 

[Boarstorm]

I think 9 or 10 is probably a safe bet.

However, one of the things [MENTION=84774]surfarcher[/MENTION]'s dissection of monster design revealed is that two 11th level spellcasters could have very different CRs. The CR is based on how many of their spells known are offensive - its a damage output calculation. So without knowing the yuan-ti's spell load out, we can only make rough guesses.

The link in the OP has the full spell load-out.

 

[Quickleaf]

The link in the OP has the full spell load-out.

Ok, you've changed more than just adding spells...

Improved multiattack (thanks to Pact Blade)
Boosted Ability Scores & HP
Boosted innate spellcasting (notably at-will Mage Armor & Circle of Death 1/day)
I1th warlock spellcasting

Improved Multiattack
Melee DPR for Yuan-Ti Abomination = 17+11+11 = 39
Melee DPR for Kersethis = 17+11+24= 52

That alone is near the max DPR for a CR 8 / min DPR for a CR 9, based on http://surfarcher.blogspot.com/2014/09/d-5e-monsters-part-7-construction-damage.html

Boosted Ability Scores & HP
Con 19 increases HP from 127 to 142. In either case, the HP exceed the typical maximum value for a CR 10 monster (115) according to http://surfarcher.blogspot.com/2014/08/d-5e-monsters-part-4-construction.html The yuan-ti abomination is a low AC, high HP monster to begin with, so gauging CR based on HP is difficult in this case.

However, the Cha 20 is very telling, as only CR 9 or 10 monsters get ability scores at 20.

Boosted Innate Spellcasting
The Mage Armor AC of 16 is consistent with a CR 6 or 7 monster based on http://surfarcher.blogspot.com/2014/08/d-5e-monsters-part-5-construction-ac.html

Circle of Death is a potent 8d6 (28) damage, but I'll factor that into the next section.

11th level Warlock Spellcasting

Cantrips (at will): mage hand, minor illusion, prestidigitation, true strike
1st level: expeditious retreat, hellish rebuke, hex
2nd level: darkness, misty step
3rd level: counterspell, dispel magic
4th level: dimension door, hallucinatory terrain
5th level: contact other plane, hold monster

I would peg him as principally a "utility/defense caster", which would mean less of an increase in CR than an "attack caster." There is no exact CR guideline, but [MENTION=84774]surfarcher[/MENTION] presents his thoughts so far over here: http://surfarcher.blogspot.com/2014/09/d-5e-monsters-part-6-construction.html
My DM instinct for this spell load out would be +1 CR.

Also, with the 5d10 (27) damage from hellish rebuke and 8d6 (28) from Circle of Death, I think that clearly pushes his DPR into the CR 9 category. Then +1 for the utility/defense casting, and...

Altogether I'm pretty confident you're looking at a CR 10 monster.

 

[Boarstorm]

Thanks for the analysis!

He's an experiment in adding class levels without adding hit dice.
The ASIs correspond with what a warlock of that level would have. I'm off - the - cuffing things and was curious how it would turn out.

At this point, though, I either need to tone him down a bit or push him father back in the adventure.

Thanks again!

 

[surfarcher]

I think 9 or 10 is probably a safe bet.

However, one of the things @surfarcher's dissection of monster design revealed is that two 11th level spellcasters could have very different CRs. The CR is based on how many of their spells known are offensive - its a damage output calculation. So without knowing the yuan-ti's spell load out, we can only make rough guesses.

My critique...

• Average attribute is a bit too high. Max attribute is slightly high, but OK.
• HP are slightly low for a CR8.
• Damage is slightly high for a CR8 - I'm assuming it'll attack thrice with Pact Blade.
• HP and Damage alone balance out to a high-CR8 or low-CR9 monster.
• I left the following out above - Spellcasting, Magic Resistance, Misty Escape & Beguiling Defenses. The last three are all defensive boosts and IMHO put this critter pretty clearly at CR9.
• Spells aren't set properly. Need to indicate how many slots for each spell level. E.g., 5th level (1 slot): contact other plane, hold monster
• The listed spells are mainly defensive and will boost the monster's Defense Index, increasing it's CR.
• Some of the spells are "remove from play" (e.g., Hold Monster) and will thus boost the monsters Offense Index, further increasing it's CR.

To me this is at least CR9, but just as likely CR10 depending on how those spells shape up.