As long as a blue Creature-centric deck exists in Standard, though, theres a good chance Subterranean Schooner is a big part of it
Extra untapped mana on an opponent's turn
Unfortunately for the galaxy, they lay claim over everything
The reason for this is the flexibility that Devotions payoff cards have
In general, the best way to play Xanathar, Guild Kingpin isn't to simply cast as many of our opponent's spells as possible but to play some cards and then try to leave our opponent with a useless card (most often a land) on the top of their deck, which is almost like making our opponent skip their next draw and, if our opponent is empty-handed, pretty close to making our opponent skip their turn
Youre guaranteed to get one Mystical Archive card in draft and set boosters