Making this work in Commander is hard, because libraries are large, variance is high, and we only have one Spark Double (The key card in Standard and Pioneer as it lets you keep spare Gyrudas around, for that Plan A of swinging in for lethal). Because it is hard, naturally, I really wanted to do it! For commander I settled on Atraxa, Praetors' Voice - I think it's definitely justifiable to do a version of this deck with Muldrotha, the Gravetide but I felt I lost out on too many "free rolls". It's also legit to do this with Gyruda in the command slot instead of the companion - but again, you lose a lot of "hits" in exchange for the ability to more consistently chain Gyruda into Gyruda over a longer, grindier game.
Below, in my initial draft, I delineate between a "free" roll and a "combo" roll. To explain...
- A free roll is a clone effect or immediate flicker effect like Restoration Angel. These allow us to immediately gain another trigger of Gyruda to roll again. We are running every single free roll available to us. Key among them is Panharmonicon, which makes us literally twice as likely to "go off" and infinite if we can stick it before slamming Gyruda.
- Combo rolls are, tautologically, not free. It's a mixed bag here. We have some pieces that require a mana investment which means waiting until much later to pull the Gyruda-trigger, like Deadeye Navigator or Mistmeadow Witch. Some only trigger on endstep, so you can't "immediately" continue, like Thassa, Deep-Dwelling or Glimmerpoint Stag. Some are "o-ring" style effects and will require a sacrifice outlet to keep the engine running smoothly, like Faceless Butcher and Hostage Taker. Some effects here bounce, which means they don't immediately continue the chain but do allow us to keep chaining in the following turn without fear of removals, like Cavern Harpy. We also have Luminous Broodmoth and Mikaeus, the Unhallowed who do nothing by themselves but are VERY GOOD with the clones; we sacrifice most clones to the Legend rule, but these two bring them back - effectively, these guys are like extra panharmonicons that don't work on the first casting.
The key thing is that we're only running stuff that Gyruda actually hits - we are eschewing stuff like Rite of Replication that only works when hardcast. I managed to find 35 total "rolls", to preserve the structure of the STandard/Pioneer decks that are running about 33% of their deck as hits. The rest of the deck is mostly support in the form of ramp, draw, and interaction, with a few additional combo pieces for good measure. As a weird rules quick, Gyruda brings back a card even if they were exiled - Demon Kraken don't care where the cards went. This means we can, and are, running stuff like Leyline of the Void to prevent opponents from surviving our infinite mill combo.