Id make a you cant play Sol Ring unless you also play Acorn Catapult rule in a heartbeat
That argumentation applies even more to Legacy than Modern since you clearly see Expressive Iteration being extraordinary in Delver, good in Control and non-existing in absurdly strong combo decks like Storm, Doomsday or Sneak & Show
From aggro decks that apply pressure to control decks that stabilize the board while adding a solid board presence, its one of the best flash cards printed in the modern Magic era
It can be slow as a 6-mana commander that needs to deal damage but can also take players out of the game
Greel, Mind Raker Greel, Mind Raker strikes me as the worst horror commander because its discard ability targets a single player, and thats ineffective in EDH
1-Mana Hexproof-Granting Instants We can lump a ton of great instants into this category to be concise