Eta, the Backstabber

You may pay 10 life to cast this card without
paying it's mana cost.
Flash, haste
{p/b} {t}: Each opponent loses 2 life
{p/g} {t}: Put a 1/1 green Saproling creature token
with haste and "{t} add {g}".
{p/w} {t}: Exile target creature. Its controller gains
life equal to that creature's power.
Whenever an opponent gains life you gain life
equal to the amount of life you have lost this turn.