honestly. I, as well as many others, think that Saint is the Triple Affirmative. Saint, upon meeting 7 of the 8 Echoes, gains the ability to ascend creatures, obliterating their bodies. This ability works on every creature in the game, even the Iterators. The Iterators have been looking for a way to ascend themselves, and Saint might've been the answer. I think that Sliver of Straw created Saint, as after sending out a Triple Affirmative, SoS disappeared. Saint could've wandered from Sliver's Superstructure all the way to the area of the world that we, the player, can explore. If this is true, then it's highly likely that Saint somehow lost their ability to ascend creatures along the way there, and regained it after reaching max karma again. Saint matches all 3 requirements of a Triple Affirmative, and starts in Sky Islands. The reason Saint was the final Slugcat was likely due to the long journey from SoS' Superstructure to the explorable part of the game world. Saint can (And might) ascend all creatures, and as such, is easily the last Slugcat in Rain World's story.