mtg blue search your library for a card Rules Text: search, target, player's, library, exile, 21 cards not actual card. Trench Gorger [Commander 2011]

There are a myriad of ways to accomplish this, with some being easier than others

They serve to give your side of the board tempo by allowing your creatures to attack (removing defenders), giving you more time to set up the board (removing attackers/expensive creatures), and allow for combat tricks (saving your creatures after damage is on the stack

There are other similar mono-color rocks in this semi cycle, but these are the best

My experiences playing the deck were a blast and it was Miara who led the charge

Norn's Choirmaster gives your Incubator tokens another buff with frequent proliferation

None of these seem very strong, plus theres the chance you mill over the perfect tutor target at some point