mtg cards like elixir of immortality Graveyard Shovel (foil) - Innistrad Shuffle Elixir of Immortality and your graveyard into your library. Elixir of Immortality | Magic

I very recently talked about the problem with Infect in Commander

Arachnogenesis was printed as part of a Commander deck, and there is no shortage of win conditions in Commander that involve making "infinite" creatures

You can craft combos that you'd never be able to pull off in a mono-blue deck, but at that point all you've done is sculpted your own 2-color combo that you could've built into an actual 2-color deck anyway

Even then, it's still nowhere as good

Lots of characters you probably can't challenge with a large amount of Evasives from Ruby and things you don't really want to challenge in Emerald's toolkit