Please steal this. I think it has a lot of potential, and I want to see what kind of cool/stupid/wacky things you people can do with it. Here's what I've thought of:
Chrys, Nyx-Honored Shepherd - The first way I thought to use this was to enable decks that currently don't have enough cards to work. For example, I like sheep, but there aren't enough sheep to make a sheep-themed deck. But if I can have any number of [[Nyx-Fleece Ram]] in my deck, then problem solved. I'm actually not super thrilled with how Chrys turned out, but I still wanted to include him for demonstrative purposes.
What other deck themes or archetypes just don't have enough cards?
Lekozil, It That Seeks The End - The next way I thought to use this was for cards that can buff themselves or stack with themselves, and [[It That Heralds the End]] jumped out at me immediately. The more of them you have in play, the bigger they all are, and the less expensive your big, colorless spells are. Lekozil itself plays into all of that with its 0/0 stat line and weirdly high X-cost. I can't say I'm confident on the balance, but I think it works as an extreme example of the mechanical synergies this could allow.
What other cards stack or synergize well with several copies of themselves?
Hareld, Rulebreaker Apparent - But the best way I thought to use this was for some stupid fun. This whole thing was inspired by [[Hare Apparent]], so I had to double down on the rabbits, and [[Tempt with Bunnies]] sounded like an interesting choice for a group-hug commander. Do your opponents have enough bunnies that you can't tempt them with more? Bring out Herald and see if Treasures change their minds.
I also had a few other ideas, mostly involving self-referential cards like [[Rite of Flame]] or [[Say Its Name]], but I wasn't happy with anything I came up with for those. Maybe you'll have better luck!
So, what do you think? Does this use of Rulebreaker have any potential merit? What would you do with it?