I don't think players can turn around with spending AP to move or using an ability unless you have The Pawn, but AI might. As far as sneak in PVP goes, it does seem like it might be hard to make useful. If you sneak and make it obvious you're right behind someone, you should be discovered easily, but if you're moving around the periphery of the combat in an unpredictable way, it should be hard to find you.
When you aim a spell/skill you could freely turn around. That is a way how a rogue will come to a cone of vision for free. More over skills like Vault, Whirlwind, Teleport wildly changes with cone of vision, so it is not possible (in current combat where everyone casts skill/spells every turn) predict where could be a cone of vision for a next turn. More over wildly spread floor elements damage you and kick out of sneak. Trying to polish sneak for wild unpredictable magic-based combat is waste time. There is no way to make it work. Or you have to overhaul whole combat from scratch.
I would rather see combine Thievery (lockpicking, pickpocketing, disarm trap, sneaking) in one skill. Such a skill is focused out of combat. Then make Shadow walk proper combat sneak.
