Dunno if this is new or old, and credits for discovering don't go to me but a ranger friend anyways:
Target a player that's standing close to a mob (or drag a mob next to him), then use multi strike. If both the player and the mob are in range to be hit, the player will take damage.
Would be nice if anyone could confirm this on other AoE's. Orc Sorcerer ones don't seem to work.