They could hold up interaction like Drown in the Loch and threats like Soaring Thought-Thief and deploy whatever was most appropriate
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Expensive wheels can take up your entire turn, but refunding a chunk of mana lets you cast some spells from your new hand, and the plus one means youre net even on cards
When you add in time for rolling and wacky effects, Planechase Commander games can take a while, too, so you should probably expect to settle in for a little longer than normal, though some of the new planes really encourage attacking and moving the game along, so maybe less than you might think if you're used to Planechase Commander already
But given that Thousand Moons Smithy comes down and makes a Karn-struct thats reasonably large right away in an affinity deck and then also likely flips the next turn, this seems like a nice artifacts top end, especially because Barracks of the Thousand is an artifact land