Minting and redeeming
Getting both sides at once, without touching the book.
Minting
One USDC mints one YES and one NO. It is the one operation that needs no counterparty, because you are buying the whole dollar rather than a side of it.
Redeeming
Handing back one YES and one NO returns one USDC, at any time, before or after resolution. Market makers use this constantly to rebalance without crossing the spread.