The lasers deal 7 damage per tick (BUG: 3.5 if Isaac has BFFS!), and can hit up to 10 times for a total of 70 damage. The wisps will not fire tears, but will each fire a thin Shoop Da Whoop! laser whenever Isaac uses it (including the wisp that was just summoned).
If Isaac is already shooting, the item immediately activates in that direction.