D&D 5E Which monsters have the most exciting powers?

[AtomicPope]

Intellect Devourer's namesake ability in 5e is terrifyingly powerful. Most Clerics make Int a dumpstat. One zzap and their Int can drop to 0 with no chance of healing because the healer now has an Int of 0.

The Intellect Devourer buddies up perfectly with a Mindflayer's Psychic Blast.

 

[CawoodPublishing]

Anything that has the new legendary powers is lethal.