how would you say...

[Tsuksìm atsawl (KaPTan)]

it's a trap!!!

and

you've activated my trap card(smug).

[Vawm tsamsiyu]

I think "it's a trap" could be
"tsa'u syep Lu"
That thing a trap be
 

[Hawnuyu atxen]

"tsa'u syep Lu"

No, syep is a verb, so it could only be "fì'u tìsyep lu".

The other one is harder (no word for "card"), but i'd say:
Nga oeyä tìsyepur tìkangkem seykìlmi.
you i-gen trap-dat work make-(causative, perfective recent past)
You just made my trap work.

Of course you can drop the <ìlm>, or change it to <alm>, <ol>, <ìy>, <ay>

['Oma Tirea]

"tsa'u syep Lu"

No, syep is a verb, so it could only be "fì'u tìsyep lu".

Although if you think about how the idiomatic "it's a trap!" is used, the reference is nore if a "that" than "this," so "tsa'u tìsyep lu!" would seem more appropriate.

[Hawnuyu atxen]

I think it would be tsa'u, if i haven't yet get in, just spotted it, but if i'm in, and i spot it too late, it should rather be fì'u.
It depends on what Tsuksìm atsawl want to say.

[Payä Tìrol]

Na'vi allows for implied subjects, why not just omit it?
tìsyep lu!

['Oma Tirea]

Na'vi allows for implied subjects, why not just omit it?
tìsyep lu!

Txantsan, how could we forget...

[Tsuksìm atsawl (KaPTan)]

as old mcdonald would say...
i ray, i ray, oooooo.