Valhalla

Valhalla enters the battle field tapped.
{t}: add {r} or {g} or {u} to your mana pool.
When a creature you control is destroyed during
combat put a soul counter on it. ( That creature
still enters the graveyard.)
Ragnarok, If you have 5 or less life, sacrifice
Valhalla, return any creatures with soul counters
on them to the battlefield from your graveyard.