Gelugon

Gelugons, also called ice devils, were the strategists and masterminds of Hell's armies. Cold, calculated logic, dictated their strategies and they'd sacrifice any numbers of infernal soldiers to achieve their aims.

Appearance
Gelugons appeared to be large, insectile devils that stood on bird-like legs. They carried frozen spears that numbed and slowed the bodies of anyone struck by their pointed ends. A gelugon stood twelve feet tall and weighed 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 named Martine and a former paladin named Vilheim.