For as long as you control Kotose, you may play one of the exiled cards, and you may spend mana as though it were mana of any color to cast it
This Ink color has a surprisingly balanced range of offensive and defensive capabilities that make it easy to build around
Esper Sentinel is probably the second best one
Iconic Cards: Counterspell, Ponder, Damnation, Jace, the Mind Sculptor Popular Decks: UW Control, Jeskai Control, Taking Turns, Esper Control 3 Midrange Midrange decks are popularly said to solve problems, not create them. In other words, these decks are sort of designed to be able to win against every archetype, although they wont bulldoze over anything (the way aggro often wrecks control, for example)
Cards from every set (except ones with a silver border or an acorn symbol) are legal in the format, making nearly every Magic card ever released allowed to be played