A card bearing this sigil will strike each opposing space that is occupied by a creature. It will strike directly if no creatures oppose it.
Omni Strike is a sigil exclusive to the final boss giants The Moon and The Limoncello, cards in Act I (in the case of The Moon) and Kaycee's Mod (in the case of both cards). A card bearing this sigil will strike each opposing space that is occupied by a creature from left to right, ignoring any empty spaces. If no creatures oppose it, it will attack the opponent directly in a single lane.
In early builds of the game, this Sigil used to be called Moon Strike.