mass-monster-instakill in just 1 card? I dont think thats going to happen.
Alternate versions (that still fit the theme):
-Permanent that deals 1dmg to non
creatures each turn (lasts 3 turns costs 5/4
or maybe even less)
-Randomize the position of monsters on the field (synergy with flooding) (may deal some dmg as well)
-bounce target creature back into opponents hand and deal 10 dmg to opponent
probably offtopic:
- soft pc (bounce back up to 2 permanents of the same kind into owners hand)