Just thinking out loud...
Do we need to be tightly packed or else our copies could appear amongst us? Do we need our defenses right up against us or else the copies appear between us and the traps? Last time, how far away from us did the copies appear?
We have Evards, Firestorm, oil and marbles surrounding us. We can add, Prayers, chants, poetics, stinking clouds, etc... before we pick up the sword. If the copies appear outside our traps they could release long range attacks at our tightly packed formation (ouch)
Will the fire affect the Evards? How badly? Should we be setting up the defenses in rows?
Can someone telekenis the sword into the bag of holding and avoid the encounter? Could we use a pre-set wall of force to keep the copies at bay as we teleport away?