Saffi Eriksdotter + Fiendish Panda + Phyrexian Altar

Saffi Eriksdotter

Fiendish Panda

Phyrexian Altar

How it works

1. Activate Saffi by sacrificing it, targeting Fiendish Panda.
2. Activate Phyrexian Altar by sacrificing Fiendish Panda, adding one mana of any color.
3. When Fiendish Panda dies, its second ability and Saffi trigger.
4. Resolve the Saffi trigger, returning Fiendish Panda from your graveyard to the battlefield.
5. Resolve the Fiendish Panda trigger, returning Saffi from your graveyard to the battlefield.
6. Repeat.