Mana Crypt costs zero to cast and immediately generates two mana which recurs every turn, though it has a chance of dealing three damage to you on your upkeep, a downside far outweighed by the absolutely ludicrous upside
It also has an incredible base rate thanks to its 3 power and three relevant keywords
This becomes a lot easier when all of your creatures suddenly have haste and become awesome topdecks in the late-game
Ironically, right before this article was published, The one-of-one serialized Ring was confirmed to have been found, so this isnt a realistic thing you can open anymore
#8 Urborg, Tomb of Yawgmoth A Commander favorite that also sees a ton of Pioneer, and some Modern play, Urborg, Tomb of Yawgmoth gives all lands the ability to tap for black mana
Universes Within cards maintain the original mechanics but with new names to fit their appearance in other sets