For the record, this is a completely untested and unrefined idea off the top of my head that I just wanted to put to paper (or in this case, type).

[Pact Package]

3x Narset, Parter of Veils
3x Leovold, Emissary of Trest
4x Force of Will
3x Tainted Pact
3x Day's Undoing


1x Brainstorm
1x Ponder
1x Preodrain
1x Serum Visions
1x Fatal Push
1x Tyrant's Scorn
1x Inquisition of Kozilek
1x Thoughtseize
1x Assassin's Trophy
1x Abrupt Decay
1x Toxic Deluge
1x Flusterstorm
1x Spell Pierce
1x Spell Snare
1x Engineered Explosives
1x Bitterblossom


1x Baleful Strix
1x Snapcaster Mage
1x Spellstutter Sprite
1x Vendillion Clique
1x True-Name Nemesis
1x Notion Thief


1x Saheeli, Sublime Artisan
1x Jace, The Mindsculptor


1x Underground Sea
1x Tropical Island
1x Bayou
1x Island
1x Snow-Covered Island
1x Swamp
1x Forest
1x Watery Grave
1x Breeding Pool
1x Polluted Delta
1x Misty Rainforest
1x Scalding Tarn
1x Flooded Strand
1x Verdant Catacombs
1x Bloodstained Mire
1x Marsh Flats
1x Wooded Foothills
1x Darkslick Shores
1x Underground River
1x River of Tears

I'll type up more on this later, but super short version: It's a Leovold BUG Value deck playing good BUG Cards, but with 3x Days Undoing that Combo with 7 other cards in the deck to lay an enormous haymaker (Your hand becomes 7, there's becomes 1 - or 14:0). Because it's otherwise made up of singleton Legacy BUG Value cards, Tainted Pact also reliably turns into a Combo Piece or Force of Will (it's pretty easy to push past one of the 3x cards you already have too, since you'd need to see the last copy to bust - Pact included).