Color Identity: B

Initial Card State
- All permanents on the battlefield.
Steps
- Activate Cauldron of Souls by tapping it, giving Dross Scorpion persist until end of turn.
- Activate Phyrexian Altar by sacrificing Dross Scorpion, adding one mana of any color.
- Dross Scorpion dies, triggering its ability, its undying ability and its persist ability.
- Resolve the first Dross Scorpion trigger, untapping Cauldron of Souls.
- Resolve the Dross Scorpion persist trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
- Activate Phyrexian Altar by sacrificing Dross Scorpion, adding one mana of any color.
- Dross Scorpion dies, triggering its ability and its undying ability.
- Resolve the first Dross Scorpion trigger, untapping Cauldron of Souls.
- Resolve the second Dross Scorpion trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
- Activate Phyrexian Altar by sacrificing Dross Scorpion, adding one mana of any color.
- Dross Scorpion dies, triggering its ability and its persist ability.
- Repeat from step 4.
Results
- Infinite colored mana.
- Infinite death triggers.
- Infinite ETB.
- Infinite LTB.
- Infinite sacrifice triggers.
Bracket Tag
This combo has been estimated to be Exhibition (Bracket 1+).