Iceball - a shadow guardian

[Sallan]

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

[nilbog]

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.