Overlord's Observance

Overlord's Observance can't be destroyed.
Whenever a spell is played, you gain 1 life, draw 1
card, add 1 mana of any color to your mana pool,
and sacrifice a permanent and put a mourn
counter on it.
When you have 10 cards with mourn counters in
your graveyard, transform Overlord's Observance.