Orb of the Firmament
From The Heroes of Might and Magic III wiki
|Orb of the Firmament|
|Effect: This powerful orb causes hero's air spells to inflict an additional 50% damage.|
|You come across a conjurer who begs to accompany you and your army awhile for safety. You agree, and he offers as payment a strange orb of the elements.|
Orb of the Firmament is a major class artifact, that is equipped in misc slot. This effect does not stack with multiples of the same artifact.