Arcbound Reclaimer + Showdown of the Skalds + Welding Jar + Bolas's Citadel

Arcbound Reclaimer

Showdown of the Skalds

Welding Jar

Bolas's Citadel

How it works

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

This clever engine runs entirely off the top of your library thanks to Bolas's Citadel, which lets you cast Welding Jar without spending any mana or life. Once that free artifact is in play, Showdown of the Skalds steps in with its second and third lore chapters to reward each spell cast by dropping a +1/+1 counter onto Arcbound Reclaimer. That counter immediately fuels Arcbound Reclaimer's ability, allowing you to pluck the sacrificed Welding Jar right out of your graveyard and place it back on top of your library to repeat the loop indefinitely.