Agroboth

Immunity to Poison, Necromancy:
This monster is naturally Immune to both Poison and Necromancy.

Vulnerability to fire:
This monster takes double damage to fire.

Stamina Stack:
The creature can choose to use "Boulder" to ball up for 2 rounds straight, taking half damage for both rounds, then it would unlock enough Stamina to use it's Legendary Action.

Bite:
+10 to hit, Opponents take 3d12 of piercing damage.

Double Swirl:
+6 to hit, The creature would Swirl it's tentacles around in a circle dealing 2d12 of piercing damage to anything in the range of 4 tiles around him.

Grapple:
+6 to hit, The monster would grapple it's opponent locking them in place and dealing 4d4 of piercing damage every round.

Boulder:
The creature would ball up for 2 rounds straight, taking half damage for both rounds, then it would unlock enough Stamina to use it's Legendary Action.

Tentacle Outburst:
+7 to hit, The creature would summon 5 extra tentacles in addition to his first 2 that would all flick around in a region of 4 tiles dealing 5d12 damage to everything around it, knocking all of them back 6 tiles.