Okay, so im itemdueling this guy named asdguy, rhymed man.
Anyway i was winning 1-0 and he suddenly says he gtg. He left and didnt compe back. Do i report him now or what?

So, how many wins have you agreed to him for the duel? I think if you're duelling someone for something else than Toricredits you have to make a make a deal on how many wins should any of you get to win the duel.

If it's only 1 win then you better PM him first before reporting him since he said "g2g" after lost the duel.
If it's more than 1 and then he said "g2g" after you won the match, I think the duel is posponed and maybe he'll continue after he done with his irl stuff. Try to PM him to make a deal about when he can be online and continue the duel.

Wait for 24 hours atleast, if he hasn't come back, you can report him with the evidence you got.

I have a feeling this guys is prtsc who scammed detacher by saying 'gtg' as well. http://forum.toribash.com/showthread.php?t=519044

It was first to 3 mang. And i was about to get my second win to make it 2-0.
And i dont think he was prtsc, hes really really bad

yea ancient report him

It's settled then, you're able to report him. Don't forget to give the evidence about the duel scam.