Its a heavily-played card in formats where its legal, and thats mostly Vintage, Legacy, Cube, and EDH, where its a Game Changer
A fixed Cranial Extraction (removing messy arcane business) Memoricide is almost surely destined to be a sideboard card
My soft rule for mulliganing with the deck is that my opening hand should have either an Elemental or Ragavan on turn one
It basically lets you double-dip on creature burn, letting you rebound the 4 damage from a Flame Slash to each opponent
In Magic, players control creatures that have two stats: "power" and "toughness"
Whats more sometimes you make a choice, it changes a previous choice, so you make the change and wind up going back to that first choice and change away from it, too