Earth

Start the game with Earth on the battlefield.
Earth cannot leave the battlefield unless there are
no sustain counters on it
Sustain 12 (This card gets 12 counters. Whenever
you are dealt combat damage, remove one. If there are
none, remove it from the game).
When earth leaves the battlefield, you lose.
{t}: Add one mana of your commander's color identity, add one more for every third land you
control.
{4}, {t}: Sustain 1