Requires

Feldon of the Third Path must be on the battlefield. Thornbite Staff must be on the battlefield. Cathodion must be in the graveyard. Phyrexian Altar must be on the battlefield. Thornbite Staff attached to Feldon of the Third Path. Feldon of the Third Path does not have summoning sickness. Mana needed:

Steps

1. Activate Feldon of the Third Path by paying and tapping it, creating a token copy of Cathodion with haste.
2. Activate Phyrexian Altar by sacrificing the Cathodion token, adding .
3. When the Cathodion token dies, it and Feldon of the Third Path trigger.
4. Resolve the Feldon of the Third Path trigger, untapping it.
5. Resolve the Cathodion trigger, adding .
6. Repeat.

Results