W.D. Gaster, Royal Scientist

Whenever another creature attacks or blocks, W.D. Gaster, Royal Scientist gains "{1}{u}: Each creature that attacked or blolcked this turn gets -0/-1 until end of turn." and "{1}{r}: Each creature that didn't attack or block this turn gets -0/-1 until end of turn." until end of turn.
When W.D. Gaster, Royal Scientist dies, you may pay {1}{u/r}. If you do, return it from the > 0/13 graveyard to the battlefield transformed.