Arcbound Reclaimer + Showdown of the Skalds + Mystic Forge + Dark Sphere

Arcbound Reclaimer

Showdown of the Skalds

Mystic Forge

Dark Sphere

How it works

1. Cast Dark Sphere either from your hand or from the top of your library by paying 0
2. Showdown of the Skalds triggers, putting a +1/+1 counter on Arcbound Reclaimer.
3. Activate Dark Sphere by tapping and sacrificing it.
4. Activate Arcbound Reclaimer by removing a +1/+1 counter from it, putting Dark Sphere from your graveyard onto the top of your library.
5. Repeat.

This clever loop turns the zero-mana artifact Dark Sphere into a self-sustaining engine by exploiting the card-casting permissions and top-deck manipulation of Mystic Forge. Whenever you replay the sphere from the top of your library, the second and third chapters of Showdown of the Skalds trigger to place a +1/+1 counter onto Arcbound Reclaimer. That counter immediately fuels Arcbound Reclaimer's activated ability, allowing you to recycle Dark Sphere from the graveyard right back to the top of your library for the next iteration.