Ice Devil

A Greater Ice Devil stands here cheerfully freezing souls..

This devil is a mix of bug, bird, humanoid, and who knows what else.
Its multifaceted eyes stare everywhere. It goes about its business of
slowly and painfully freezing the damned souls, quickly thawing them
and then starting over. Every couple of minutes it takes time out to
break an appendage off of a nearby soul and beat the soul with it.

Ice devil is using:
a brazier of unholy blue fire
ice spear