Blood Rain Bow

Nothing leaves the bow itself. The blood falls from above wherever you point, so anything with a roof between you and the sky kills the entire attack. In a cave or a boxed arena it is close to useless, and out on the surface it hits ground no other pre-Hardmode bow reaches. The streams also stop on the first block they touch, so even a platform ceiling over an enemy will eat your shot.

Nothing about the arrow survives the conversion except its damage number. Jester, frostburn, holy, none of those effects carry through, so loading anything expensive is wasted. The odd exception is speed: the falling streams take part of their velocity from the arrow, and the arrows you would think of as slow end up producing the fastest rain.

Only one arrow leaves your stack per shot regardless of how many streams appear, so it stays cheap to run even when you are firing constantly.

Turn blood and gore off in the settings and the whole effect becomes gray clouds instead. The tooltip is a Slayer album title with the spelling changed for the pun.