Was I wrong to not include a saving throw in this encounter?
I had a bit of a polarizing boss fight. Group of 4, we've all been playing like 10 years. They show up to BBEG, last session of the campaign, who has an amulet that sets off an illusion spell which made the players swap bodies. Mechanically I told the group to give their character sheet to the person on the left, "dont tell anyone how to play your character". 2 of them loved it. Their jaws hit the floor, they got all excited etc. The other 2 got upset because I didn't have them make a saving throw. Under normal circumstances I'd have done the throw, but the whole swap was kinda the gimmick of this entire encounter. Else it would have just been a standard fight with an orc with flaming swords. I told them my rationale, and to just roll with it and have fun with it, but they spent the entire boss fight irritated.
I guess I could have deceived them with an impassable saving throw but that's not really my style.
I dunno what do you guys think? Was I wrong?
EDIT: I just wanna clarify the campaign wasn't very long. About 5 sessions. So I wasn't expecting a ton of attachment to their characters. I would not have done this in a longer campaign as the final boss fight. We've been playing as a group for a long time, but this specific game was short.