For this post I had to find a suitable ‘I’ monster inside another letter (‘D’ for Devil) because I find that the only two entries in the manual are dull and uninspiring.
Ixatuloth is an Ice Devil who resides in the real world (of your campaign). Like most of his kind, he revels in causing mayhem and destruction, but he also hates other Devils and their earthly allies with a passion: he uses a network of spies to root them out and destroy them.
Unfortunately, this perpetual caterpillar stage is forbidden in the Infernal Hierarchy (it breaks too many rules, funny enough). Ixatuloth is one such creature who was banished and stripped of all his inherited titles in Hell’s nobility.
In the real world, he has developed a following: mostly thieves, spies, assassins and courtiers who he’s deemed competent enough in his tasks to wreck the mortal world and also to cause all sorts of unpleasantness to other Devils and their worshippers. Several witch-trials and inquisitions were actually his doing.
However, because he does not want to be found out, he’s planted careful rumors and lies into the minds of civilization; most people denounced these grim hunts and labelled them as cruel acts of corrupt religious leaders. That mentality has protected Ixatuloth and his followers splendidly.
Using this NPC
This Ice Devil is irredeemably cruel and evil and would serve well as a villain. However, any adventurers at odds with Devils or evil cults may find him a helpful ally (the enemy of my enemy etc…).
Ixatuloth rarely shows himself; he prefers the use of proxies: intelligent, clever and well-spoken men and women who pretend to be revolutionaries, inquisitors or other types likely to support ousting corruption or devil worshippers from society.
Ixatuloth has the same stats as a regular Ice Devil except his movement is only 5ft. Any benefits that regular Ice Devils have (hard exoskeleton, ice spears etc…) he can reproduce entirely in the form of his potent mental powers.