Cancer

Holy Aura. Infernal creatures immediately become frightened upon seeing Cancer. They must succeed in a WIS saving throw (DC 14) in order to be cured of the condition.

Aspect of the Moon. Spells that deal fire and lighting damage have no effect, while spells that deal radiant and cold damage can double the hit dice of damage dealt.

Crustacean plating. Cancer's tough plating renders it immune to piercing and slashing damage, as well as being constantly under a stoneskin spell.

Tough blood (3/per day). Cancer can choose to autommatically succseed in a CON saving throw that he makes.

Malice of Cancer. Any creature that consumes Cancer's blood, flesh or makes contact with any part of Cancer ends up poisoned.

Word of the Ancient. Cancer speaks in a language only understood by those touched by the outer planes. Any creature outside this category must make a Wisdom saving throw (DC 14). Those that fail become frightened.

Multiattack. Cancer attacks up to three times (roll 2d4, pick the highest number aside from 4) in a single turn.

Claw bash. Cancer swings down with a powerful claw. Those who are hit by this attack get their AC temporarly reduced by 2. (Attack: +5 to hit, range: 5ft., 1 target. Hit: 1d12+5 bludgeoning damage) 

Gulliotine. Cancer reaches with its claws to choke a target. If the attack is successful, the creature will be considered grappled, taking 1d4 damage at every failed save (STR, DC 15). (Attack: +5 to hit, range: 10ft., 1 target. Hit: 1d8+5 bludgeoning damage)

Crabhammer. Cancer hammers both of its claws on the ground, making all creatures within a 60ft. square of it take 2d8 bludgeoning damage or take half the damage upon a succeeded DEX saving throw (DC 14).