Gnoll Warmaster

{r}{r/g}: this creature has +1/+1 until end of turn
This creature gets +0/+1 for every green card on
the battlefield
This creature gets +1/+0 for every red card on the battlefield
This creature costs 1 less for every blue card on
the battlefield
When this creature enters the battlefield, you gain
life equal to all the white creatures on the battlefield and the black creatures in all
graveyards