Ferith Dasos, Golgari Poisoner

Eminence -- As long as Ferith Dasos, Golgari Poisoner is in the command zone or on the battlefield, whenever you cast an elf creature spell you may pay {1}. If you do it enters the battlefield with a +1/+1 counter on it.
{x}, {t}: All elves get -X/-X until end of turn. At beginning of the next combat step, elves you control get X times two +1/+1 counters.