Grafted Scion

Flash, Haste
As an additional cost to cast this spell, you may {1} pay up
to X times where X is the amount of creatures that died this turn. This enters with an amount of +1/+1 counters equal to the additional mana spent on it.

Whenever Grafted Scion attacks, you may exert it, if you
do it gains doublestrike until end of turn.
{1}{w}{r}: This gains +2/+0 until end of turn.

Whenever a creature dies, you may pay {1}, if you do put a +1/+1 counter on this creature.