
Search target player's library for up to X cards, where X is the number of Swamps you control, and exile them. Then that player shuffles.
Nightmare Incursion has 1 printing, first in Eventide (2008). EDHREC ranks it #22,482 among Commander cards. It appears most in The Madcap Jester decks (187 on EDHREC). It has 1 official ruling.
Deck counts from EDHREC.
Cards that show up in the same decks on EDHREC.