Marching Frontier

Play this land only if a creature left the
battlefield this turn.
Attacking creatures you control have hexproof.
{t}: Add {w}, {r}, or {g} to your mana pool.
{t}: Remove target creature you control from
combat. Untap it.
"Tragic, that we forget the heroes that gave their lives
in battle..." -Shtratos, Prince of the Naya.