Probability this is Lu taking over: 99.9%

Possibility this is Agatha pretending to be Lu because she's seen something that makes her think acting like Lu and disabling everyone will draw a hidden mastermind out of the woodwork where she can deal with him/her: .1%. And I think this only because Lu isn't a good hand to hand combatant, and yet Trelawney got disabled by a kick before she, who IS supposed to be a good HtH fighter, could stop her.