How can you create a combo with Mikaeus, the Unhallowed, Putrid Goblin, Phyrexian Altar?
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[START OF COMBO]This combo can be formed with Mikaeus, the Unhallowed, Putrid Goblin, Phyrexian Altar

Color identity: B
Mana cost: 
Steps:
  1. Activate Phyrexian Altar by sacrificing Putrid Goblin, adding one mana of any color.
  2. Putrid Goblin dies, triggering its persist and undying abilities.
  3. Resolve the persist trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
  4. Resolve the undying trigger, doing nothing.
  5. Activate Phyrexian Altar by sacrificing Putrid Goblin, adding one mana of any color.
  6. Putrid Goblin dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
  7. Activate Phyrexian Altar by sacrificing Putrid Goblin, adding one mana of any color.
  8. Putrid Goblin dies, triggering its persist ability, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
  9. Repeat from step 5.[END OF COMBO STEPS]

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

Other prerequisites:
  - All permanants must be on the battlefield
[END OF COMBO PREREQUISITES]
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