How can you create a combo with Gravecrawler, Rooftop Storm, Altar of Dementia?
user
[START OF COMBO]This combo can be formed with Gravecrawler, Rooftop Storm, Altar of Dementia

Color identity: UB
Mana cost: 
Steps:
  1. Activate Altar of Dementia by sacrificing Gravecrawler, causing target player to mill two cards.
  2. Cast Gravecrawler from your graveyard by paying {0}.
  3. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite enters the battlefield
  - Infinite leaves the battlefield
  - Infinite mill
  - Infinite sacrifice triggers
  - Infinite storm count[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
  - You control at least one additional Zombie.
[END OF COMBO PREREQUISITES]
assistant