I'd do what I do whenever I'm in doubt : scan the MC moves' list.
"So there's Dremmer's coming in, but he's all acting weird, like not making eye contact and keeping his head low, and then he spots you and leaves like his ass's on fire or something, what'd do you do?" (Separate fake!Dremmer and the PC)
"...and when he leaves you notice your bag's gone. What'd you do?" (Take away the PC's stuff)
"...so you follow him and just when you turn around you feel a gunpoint between your shoulders and Dremmer says — with a voice that's definitely not Dremmer's — “Boss wants you dead, no hard feeling, a'right?" (Fake!Dremmer is some Warlord's agent, and he just made a careful study of you and then attacked when you're weak)
"So here's Dremmer and he's cocky as always, he comes in like he owns the place and all, he smiles at you and then WHAM with the biggest smile and his hand moving so quick you barely see it he sticks his big-ass knife in your guts! Everyone around is like "wait what ?" You take 2-harm. What'd you do?" (Fake!Dremmer is a grotesque:mindfucker who can shapeshift — he just attacked you face-on, with a side-dish of inflict harm for good measure)
"You've just said that to Dremmer and this guy, Balls you think he's called, shakes your shoulder and ask you "hey, man, who you talking to ?" and when you look back to Dremmer, he's not there man, like he never was." (Landscape:mirage, revealing fake!Dremmer to your eyes and yours only)
Or something like that.