Mazirek, Kraul Death Priest

Flying
Whenever a player sacrifices another permanent, put a +1/+1 counter on each creature you control.

Ashnod's Altar

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Cleopatra, Exiled Pharaoh

Allies — At the beginning of your end step, put a +1/+1 counter on each of up to two other target legendary creatures.
Betrayal — Whenever a legendary creature with counters on it dies, draw a card for each counter on it. You lose 2 life.

Sol Ring

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.