Rat Plague

Whenever a enemy casts a creature spell create X
1/1 black Rat Creature tokens with "This
creature can't block.", where X is that creatures
power.
Whenever a Rat creature dies all opponents loose
2 health, and you gain 2.
{2}{b}: Create a Plague token with "equipped Rat
gains +2/+0 and when this creature dies target opponent loses 4 health, and mills 4 cards."
on target Rat.