How can you create a combo with Mephidross Vampire, Walking Ballista?
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[START OF COMBO]This combo can be formed with Mephidross Vampire, Walking Ballista

Color identity: B
Mana cost: 
Steps:
  1. Activate Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to any creature an opponent controls.
  2. Walking Ballista triggers, putting a +1/+1 counter on itself.
  3. Repeat as desired.
  4. You may also repeat this loop whenever a creature enters the battlefield under an opponent's control.[END OF COMBO STEPS]

Result:
  - Destroy all creatures that enter the battlefield under an opponent's control
  - Destroy any number of creatures opponents control
  - Infinite damage to creatures[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
  - Walking Ballista has at least two +1/+1 counters on it.
[END OF COMBO PREREQUISITES]
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