Urzas Filter (INV nonfoil $4) If youre casting and copying multicolor spells, this is your new best friend
Red Bulk Arcbond Flamerush Rider Outpost Siege Alesha, Who Smiles at Death 1 Month: $1-$3 Dragons of Tarkir: $1 or $3-$5+ Daghatar the Adamant Monastery Mentor Battle Brawler From Jund reanimator returning Hornet Queen to midrange returning Courser or Rabblemaster or Monastery Mentor to aggro returning Eidolon or Swiftspear or Battle Brawler, there are a variety of shells in a variety of colors that would be more than happy to pay Aleshas trigger
Foundations Foundations play boosters get extra power to their rank because they resist to rotation out of Standard more than any other set, a bit like that video game console with the promise of backwards compatibility
To make things more confusing, some cards in certain Commander sets could only be found in the (non-draftable) boosters for the main set, and not in the accompanying precons
Yorion/Doom Foretold decks are predominantly reactive decks with a few wincons, and it hasnt been quite proactive enough to compete with most of the tier-one decks in Historic
Historically, the Reserved List cards (like Dual Lands and the Power Nine) hold value best
