Killed about 110 of these, never once saw an Iceball drop from them. Wiki and Allakhazam say they should be dropping from them too alongside the blizzard and snow dervishes
Iceball can drop from any of the above mentioned npcs. It's on a table with the rest of the items they can drop (ring of frost, frozen mantle etc), so it's possible to not see one for a while.
Iceball - a shadow guardian
Linear Mode
