Requires

Steps

1. Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Geralf's Messenger.
2. Activate Phyrexian Altar by sacrificing Geralf's Messenger, adding one mana of any color.
3. When Geralf's Messenger dies, its undying ability and Serrated Biskelion trigger.
4. Resolve the Serrated Biskelion trigger, untapping it.
5. Resolve the Geralf's Messenger trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. When Geralf's Messenger enters the battlefield, it and Thran Vigil trigger.
7. Resolve the Geralf's Messenger trigger, causing an opponent to lose 2 life.
8. Resolve the Thran Vigil trigger, putting a +1/+1 counter on Serrated Biskelion.
9. Repeat.

Results