Experience Tumblr like never before
Sometimes I see people say that using persusion on Astarion to talk him out of ascension is a bad thing. Like it's mind control, but honestly, 15 is not a hard DC, that is a task of moderate difficulty. It is harder to get Wyll to smooch you at the party, or to get Shadowheart not to mercy kill her parents then to convince Astarion that mass slaughter is a bad idea and he doesn't need to do this.
Also, it's literally just talking. It's just being convincing, all the skill is is assigning a number value to how well Tav can articulate a point.
If Larian wanted it to be a difficult they would have given it a Dc 20, and if Larian wanted it to be mind control it would have been illithid wisdom.