Tested a draft, ended with Esper Control with Unburial Rites vs Grixis Tempo with Counter-Top. Counterbalance failed to counter a single card. Hence Portent. It's difficult to play two-color decks, making the mono-colored lands unplayable.

To improve the performance of some of the cards we have made the following alterations:

Arcane Sanctum/Crumbling Necropolis/Frontier Bivouac/Mystic Monastery/Opulent Palace/Seaside Citadel: Added the appropriate land types and "Cycling "; i.e. Frontier Bivouac is Ketria Triome.

Portent: Instant.
Nimble Obstructionist: Stifle effect occurs when cycled or when it enters the battlefield.
Tragic Lesson: Costs to cast.
Champion of Wits: Costs to cast, and to eternalize.
Silundi Vision: Costs to cast.
Supreme Will: Costs to cast.
Think Twice: Costs to cast, and to flashback.
Trinket Mage: Costs to cast.
Firebolt: Instant, and costs to flashback.
Terminus: Costs to cast.
Grave Titan: Is a Legendary creature.
Unburial Rites: Costs to cast.
Spell Queller: Does not cast the exiled spell.
Oko, Thief of Crowns: +2 is a +1; +1 is a -1.
Rise // Fall: Has fuse.