How can you create a combo with Sengir, the Dark Baron, Agatha's Soul Cauldron, Walking Ballista?
user
[START OF COMBO]This combo can be formed with Sengir, the Dark Baron, Agatha's Soul Cauldron, Walking Ballista

Color identity: B
Mana cost: 
Steps:
  1. Give Sengir deathtouch, if needed.
  2. Activate Sengir using Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to any creature an opponent controls, and killing it due to Sengir's deathtouch.
  3. When the creature dies, Sengir's first ability triggers, putting two +1/+1 counters on it.
  4. Repeat from step 2 as desired.[END OF COMBO STEPS]

Result:
  - Destroy all creatures that enter the battlefield under an opponent's control
  - Destroy all creatures opponents control[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Sengir, the Dark Baron must be on the battlefield
  - Agatha's Soul Cauldron must be on the battlefield
  - Walking Ballista must be exiled
  - Sengir has at least one +1/+1 counter on it.
  - You have a way to give Sengir deathtouch.
[END OF COMBO PREREQUISITES]
assistant