Masters Edition III

City of Shadows

{T}, Exile a creature you control: Put a storage counter on City of Shadows.
{T}: Add {X} to your mana pool, where X is the number of storage counters on City of Shadows.

{T}, Exile a creature you control: Put a storage counter on City of Shadows.
{T}: Add {C} for each storage counter on City of Shadows.

The Dark

oc
T: Sacrifice one of your creatures, but remove it from the game instead of placing it in your graveyard. Put a counter on City of Shadows.
oc
T: Add X colorless mana to your mana pool, where X is the number of counters on City of Shadows.