Gelugon

Ice devils, also called gelugons, are the strategists and masterminds of Hell’s armies. They make their decisions based on cold, calculated logic, with no thought of the losses of troops. As long as success to possible with their plans, they are willing to sacrifice any number of infernal soldiers.

Appearance
Gelugons appear to be large, insectile devils that stand on bird-like legs. They carry frozen spears that numb and slow the bodies of anyone struck by their pointed ends. A gelugon stands 12 feet tall and weighs 700 pounds.

In the Realms
A gelugon named Vreesar led an attempt to conquer Toril from a portal in the Great Glacier in 1366 DR. He was stopped by a Harper ranger and a fallen paladin.