User blog comment:Deedlit11/Googology in Magic: the Gathering/@comment-24920136-20161102204838

These articles are really interesting. I'll try to build one myself for the EDH variant, EDH is 99 card singleton(one of each card) plus 1 commander, the deck is restricted to the commanders colors. Play is modified to include a commander zone, where the commander starts play, if a commander would die or be exiled, a player can choose to have it go back to the commander zone instead. Casting the commander costs 2 additional colorless mana each time beyond the first. Its not uncommon to find this mechanic as part of an infinite combo, for example a dragon called Prossh spawns tokens on cast, so if you have a way to sac for mana its easy to land infinite tokens.

tldr. It'd be interesting to see how far recursion can go for a commander deck under this challenge's rules.