Rain of Revelation With the mana advantage generated by Rewind, the only thing stopping flash decks from completely locking out opponents is their ability to draw enough counterspells and lands
Theres a reason Tolarian Academy is banned in nearly every format, including Commander
This means by default, Im adding one-mana Goblins to my deck in this order: Skirk Prospector, Fanatical Firebrand, Goblin Banneret, Rigging Runner
In a big-mana deck like Hydra tribal, you can easily set that X to eight or higher, effectively ending the game on the spot as you cast up to eight enemy spells for free
Being able to split them up is lovely too, you can dig for lands early and then cash in lands with it late
Avoid Fate is one of the best protection spells you can get in a non-blue Commander deck, and nobody is ever expecting you to hard-counter their Darksteel Mutation or Imprisoned in the Moon with a 1-mana green counterspell