Interesting note: Rift Seeker has Cultist, so once it's shuffled in you can use it as a target for Mysterious Chanting that doesn't speed up the doom clock the turn it enters play.

Aside from that neat little interaction, Rift Seeker is honestly pretty basic; no Hunter if you decide to evade it and leave it behind, no "Spawn:" instructions spawning it at a different location preventing you from dealing with it, not even Retaliate in case you fail the 3 (or 4 once The Entity Above, The Entity Above, or Swallowed Sky enters play) test to hit it. Yes, it does have the Parley option, but that's a trap, paying a high cost (2 horror and 2 doom) for something that's honestly not that difficult (defeating a slightly tougher Ravenous Ghoul). Assuming you don't draw the against it, you can fairly safely treat Rift Seeker's text box as blank, except for Traits: those actually make it interesting, allowing you to fish out a (moderately) tougher Cultist with Mysterious Chanting in exchange for no doom entering play.