While its absolutely vital for Magic to experiment, even though treading into the unknown risks mechanics both broken mechanics and underwhelming, Companion proved a damaging, deeply flawed mechanic
Allowing you to find and play even more legendary creatures for free, Jodah, the Unifier can quickly spiral out of control
If we add on the tutors and cards like Land Tax, thats a much more comfortable 88.2%, ignoring how Land Tax basically gives us 100% hit rate on land drops if we have it
Erase (Not the Urza's Legacy One) Liberator, Urza's Battlethopter Tawnos, Urza's Apprentice Urza's Armor Urza's Avenger Urza's Bauble Urza's Blueprints Urza's Cave Urza's Chalice Urza's Command Urza's Contact Lenses Urza's Dark Cannonball Urza's Engine Urza's Factory Urza's Filter Urza's Fun House Urza's Guilt Urza's Hot Tub Urza's Incubator Urza's Mine Urza's Miter Urza's Power Plant Urza's Rage Urza's Rebuff Urza's Ruinous Blast Urza's Saga Urza's Science Fair Project Urza's Sylex Urza's Tome Urza's Tower Urza's Workshop
Madness decks are the obvious home, but recent cards like Inti, Seneschal of the Sun and Rielle, the Everwise have expanded the list of cards that encourage you to discard cards