How can you create a combo with Yedora, Grave Gardener, Ashnod's Altar, Watcher of the Roost?
user
[START OF COMBO]This combo can be formed with Yedora, Grave Gardener, Ashnod's Altar, Watcher of the Roost

Color identity: GW
Mana cost: 
Steps:
  1. Activate Ashnod's Altar by sacrificing Watcher of the Roost, adding {C}{C}.
  2. When Watcher of the Roost dies, Yedora triggers, returning Watcher of the Roost from your graveyard to the battlefield face down as a Forest land.
  3. Activate Watcher of the Roost by tapping it, adding {G}.
  4. Activate Watcher of the Roost's morph ability by revealing a white card from your hand, turning it face up.
  5. Watcher of the Roost triggers, causing you to gain 2 life.
  6. Repeat.[END OF COMBO STEPS]

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

Other prerequisites:
  - All permanants must be on the battlefield
  - You have at least one white card in hand.
[END OF COMBO PREREQUISITES]
assistant