Archway of Innovation With Archway of Innovation, you get two key things: a blue source and the ability to give your spells improvise
Getting to play someone elses hand during your own turn
It also discards the top five cards of each player's deck
You see, you get to choose two Creature cards in your graveyard, then sacrifice a Creature you control to return those two Creatures to the battlefield tapped
Mairsil demands a high level of skill, strategy, and keeping track of what the heck abilities they have
On top of that, each creature you steal becomes a mercenary, meaning you exile more and more cards as turns pass, especially when you run a mercenary-themed deck or effects that focus on stealing creatures from your opponents in other ways