Karn, Silver Golem, Masticore, Memory Jar, and Mox Diamond in From the Vault: Relics
Mirror Entity
Im not sure however how this affects the scale of grey on the remaining stamp
Augur of Autumn is much less of a factor for red decks, and theres no right or wrong way to approach this balance, but I do think that its meaningful to think of Courser as an anti-red card and decide how much you care about that sort of thing
Creatures (8) Planeswalkers (3) Lands (16) Spells (33) 1 Sensei's Divining Top 1 Brainstorm 2 Mana Drain 1 Vampiric Tutor 1 Yawgmoth's Will 4 Force of Will 1 Sol Ring 1 Demonic Tutor 1 Time Walk 1 Ancestral Recall 1 Mana Crypt 1 Time Vault 1 Merchant Scroll 1 Tinker 1 Voltaic Key 1 Black Lotus 1 Mox Emerald 1 Mox Jet 1 Mox Pearl 1 Mox Ruby 1 Mox Sapphire 3 Thoughtseize 4 Spell Pierce 1 Nature's Claim While The Deck had to play a playset of Swords to Plowshares and a playset of Disenchants, saving Demonic Tutor for restricted cards, eventually, things got so powerful that you could just play decks with a single creature kill spell and a single Disenchant effect
Finding Mirrorpool or Mortuary Mire leads to some interesting recursive options