Waste-Gorger Nephilim

At the beginning of your pre-combat main phase,
add a number of mana to you pool in any combination of {w}, {b}, {r}, and {g} equal to the
number of land cards in your graveyard.
At the end of your pre-combat main phase,
Waste-Gorger Nephilim gets +1/+1 for each
mana in your pool.
When it awoke, the very ground trembled in fear.