How can you create a combo with Agatha's Soul Cauldron, Walking Ballista, Butcher Ghoul?
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[START OF COMBO]This combo can be formed with Agatha's Soul Cauldron, Walking Ballista, Butcher Ghoul

Color identity: B
Mana cost: 
Steps:
  1. Activate Butcher Ghoul using Walking Ballista's second ability by removing a +1/+1 counter from it.
  2. Repeat step 1 until Butcher Ghoul has no +1/+1 counters on it.
  3. Resolve all Butcher Ghoul abilities dealing 1 damage to Butcher Ghoul, and any remaining damage to any target(s).
  4. Butcher Ghoul dies as a state-based action due to having 0 toughness.
  5. Butcher Ghoul's undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
  6. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite death triggers
  - Infinite enters the battlefield
  - Infinite leaves the battlefield[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Agatha's Soul Cauldron must be on the battlefield
  - Walking Ballista must be exiled
  - Butcher Ghoul must be on the battlefield
  - Butcher Ghoul has at least one +1/+1 counter on it.
[END OF COMBO PREREQUISITES]
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