I'm about to use an avatar of Blibdoolpoolp in an upcoming finale to a dungeon and thought I'd post her here to gather any thoughts on balance or anything else, its good to share.
The party she is facing are 5 in number and at level 9, this encounter will be a final battle, nothing to lose affair. It may be in the open air or in a semi aquatic dungeon depending on what happens.
The DMG p274 has instructed the bare bones of this creature, setting AC, DCs, HPs and the like and a CR13 or 14 creature is the highest a party of 5 9th level characters could face without it being a Deadly encounter. That's not to say I won't add a couple of kuo toa minions to get in the way...
Anyway, I appreciate the feedback:
Avatar of Blibdoolpoolp
Dungeon Module D2 shrine of the Kuo-Toa may provide some insight if you can find it on the web. I think you have done a nice job with this.
Looks good in general, but damage seems low for a CR13 monster. Should be 81-86 and you are in the 45 range + call lighting (which I don't have in front ot me). I would probably give it resistance to non-magical weapons and magic resistance as well. I feel like it will fall quickly if it doesn't get some extra protection depending on the size and strength of your PCs.
Looking at the Monster Mythology book stats I would also give:
Damage Immunities: Poison
Condition Immunties: Poisoned, paralyzed, restrained
You might want to consider the summoning feature detailed on page 68 for devils. Except use Giant crabs and Water elementals. The Monster Mythology book has 2d8 giant lobsters and 1d4 water elemetnals. I would recomend adjusting the summoning capabilities based on encounter difficulty targets.
I would recomend a CR 15 creature based on the math assuming your PCs have point buy stats or standard array. I would recomend CR 16 if you have PCs with well above average stats due to rolling. Adjust her CR lower based on the median number of water elementals you would choose she could summon. I would not adjust the CR based on the number of giant crabs she could summon.
Check your HP on the creature. It's listed at the min value for a CR 13 creature. The creatures effective HP is increased by 25% due to Horrifying Visage. The creatures effective HP is increased for Legendary Resistance per page 280 DMG. You may want to consider increasing her effective AC by 1 or 2 due to the Curse of the Deep feature, refer to Troglodyte Stench for comparison.
I agree with Dave2008. Double check the effective damage per round.
Thanks for the suggestions. I was a little worried about the HP value and DPR of the creature at that CR but as it was written its average of it's defensive CR and offensive CR worked out to about 12 or 13. I'm not usually a stickler for rules, prefer to just feel it out, but thought I'd give it a go.
I like the giant crab idea, they could be clinging to her like a cloak when she appears and rinse off in a tide of pincers and nipping legs.
Anyway, CR has increased by 1, no change to HP or AC. I've added:
Melee damage increased by one die to 2d10 from 2d8. Don't forget it's likely Blibby will be using tentacle lash every round as well as call lightning and both claw attacks.
Damage Immunities: acid, lightning, poison
Condition Immunities: poisoned, paralysis, charmed, restrained
Immutable Form. Blibdoolpoolp is immune to any spell or effect that would alter its form.
Magic Resistance. Blibdoolpoolp's has advantage on saving throws against spells and other magical effects.
Magic Weapons. Blibdoolpoolp's weapon attacks are magical
Ironxxx wrote:
Yeah it was an oversight, well spotted 
I'll change the melee damage and maybe the AC on the fly I think, depends what the group does. It'll be the first Legendary I've used (and the group has faced) and we've been playing twice a week since the middle of last year so it's quite exciting!
Thanks for the input, much appreciated.
Ironxxx wrote:
The encounter went well, the less knowledgable players were kept guessing as to how this monstrosity was hitting them back and so on as they had no idea about Legendary creatures. Two players went down several times, others were slowed or Frightened for much of the fight and they were really bricking it to be fair. The wizard only survived through Blink, the cleric only survived due to a potion and a Divine Boon they've had for ages from 4e. Blibby was faced off by the EK/Pally while the party's drow assassin climbed onto Blibbys back and did a Legolas using the alt DMG rule and the other fighter was held up by the crabs.
I also added some prisoners that they had to defend. We had a great background Cthulhu soundtrack going too, was awesome. Damage wise i think it was about right though if the players were any higher I'd switch it up to 4d6+8 from 2d10+8 definitely. I used the token below in Roll20, worked very well.
All in all it was really memorable and something we'll be talking about in the future I'm sure, thanks again to everyone who helped out on this thread.
Shouldn't everything still be in line with ability mod + proficiency. Some of the stuff adds up, others don't. STR save and Atheletics should be +11. Spellcasting DC should be 17: 8 + CHA (4) + proficiency. She's not proficient with her own claws? But you still give her a +2 to her STR mod to hit and damage? Just doesn't make sense to me. Her claw and tentacle attacks should be +11 17(2d10+6).
Obviously the fight is over and it went how it went, but I just thought I'd throw my thoughts in on this. Just in case you make more monsters in the future.
Some of the values are taken directly from the Monster Design table p274 of the DMG which I started using as a baseline so yeah it looks a bit squiffy, but thanks for pointing it out. I've actually gone through and modded it based on your suggestions so it fits more in line with Prof+stat but it wasnt entirely necessary - was great to play, felt balanced and my players had a great time
Ironxxx wrote:
You can also print out the free "Monster Manuals" for Hoard of the Dragon Queen and Rise of Tiamat, and look over the adult dragons for a similar-CR monster.
In my (limited) experience, Flight is more important than Multi-attack for making a monster hard to beat.