Abzan Ascendancy + Nether Traitor + Phyrexian Altar

Abzan Ascendancy
Nether Traitor
Phyrexian Altar

Requires
All permanents on the battlefield.
Steps
  1. Activate Phyrexian Altar by sacrificing Nether Traitor, adding b
  2. Nether Traitor dies, triggering Abzan Ascendancy's second ability, creating a 1/1 Spirit creature token
  3. Activate Phyrexian Altar by sacrificing the Spirit, adding one mana of any color
  4. The Spirit dies, triggering Nether Traitor, causing you to pay b to return Nether Traitor from your graveyard to the battlefield
  5. Repeat
Results
Infinite colored mana. Infinite ETB. Infinite LTB. Infinite death triggers. Infinite sacrifice triggers.