Overall) - Future Sight with a shout out to One with the Multiverse Next is this five-cost hard to cast enchantment that was so good it dominated the era of things like Five Color even though it was harder to cast there but was valued alongside Mirari's Wake as the best option to drop for free from an Academy Rector or in power
one (1) foil double-sided token.
Or you could, you know, target a Sharding Sphinx
Longer answer: Coven is an ability word , and as such it varies from card to card
Fire// Ice and Electrolyze There are a lot of people out there for whom Fire // Ice remains the best split card of all time, due to its iconic tournament status, including Vintage, Legacy and Standard
Creatures (3) Planeswalkers (6) Lands (16) Spells (36) 1 Brainstorm 4 Oath of Druids 4 Force of Will 1 Sylvan Library 1 Sol Ring 1 Time Walk 1 Ancestral Recall 1 Gush 2 Pyroblast 1 Black Lotus 1 Mox Emerald 1 Mox Jet 1 Mox Pearl 1 Mox Ruby 1 Mox Sapphire 1 Ancient Grudge 1 Mindbreak Trap 3 Preordain 3 Mental Misstep 1 Gitaxian Probe 2 Flusterstorm 1 Treasure Cruise 1 Dig Through Time 1 Damping Sphere Inferno Titan is that big of a game