Alright so first of all, Percy had a plan to kill Scanlan and basically the only thing that saved Scanlan’s life was the loving mercy of one Vex’ahlia de Rolo. Percy does not have a plan to kill anyone else in VM because he’s not actually Batman but also because he wasn’t angry at anyone other than Scanlan. Mostly for projection reasons and abandonment issues.
But I’ve been thinking about it ever since Taliesin mentioned it and honestly? At first you’d think there’s no way Scanlan would lose a fight with Percy but… It’s not actually that hard for Percy to kill Scanlan? Like, at all.
I agree with everything except the terrain. Unless Percy somehow stole the scrying eye from Keyleth, managed to use it regularly, and waited until Scanlan was terrain that was in favor of this plan, he had no way of choosing the terrain after his spies lost track of Scanlan. Only way to find him was to use the gate stone. Hm. And that emits pretty strong light, likely killing the surprise round. +11 initiative and action surge are still a thing, though.
(Also consider Kaylie would be around for this as well. And she seems very experienced with melee weapons.)