Toxic Mage

Split Second (This spell can't be countered)
Whenever a creature you control dies you
may pay {p/g}{p/g} to put a Toxic counter on
this enchantment. This has {x} Ward
equal to the number of counters.
{g/u}{r/g}: Remove a Toxic counter to place two
-1/-1 counter on target creature as a sorcery.