kigmatzomat
Hero
Morrus said:As Navar mentioned, the fake queen ploy has already been used. Can't do that again!
Personally I believe in using a decent tactic whenever it works. I guess the question is: what are the NPCs goals? What does the the Gith Queen want/get and what does the Slaad King want/get? We know you're after a beat-down but not a TPK so I think more character motivation is required before we can come up with a decent way to not kill the PCs.
The NPCs are just too tough and too smart to NOT be able to kill the PCs when they walk into a trap. The Queen's minions have fought the party so she has intel on their abilities and can plan for their general power level. Without any more information the best non-TPK I can come up with is capturing them to be used as food for the lich-queen or as the sacrifice in some ritual.