I find that the #1 counter for a Wraith’s decoy is for support to pop their cloak. While it does have a long CD, it will protect you from at least x2 decoy’s if the Wraith’s just spamming them. This is also great if the timer’s started and you need to buy time 'till ya win by default. Also: don’t forget about Caira’s speed boost. It falls in line with a supports cloak, but again it’s all about mitigating damage and buying time.
Don’t forget about good 'ol Hank either. If your group’s spread out, his shield will just eat up decoy after decoy attack. Also: Markov is also a good choice if the Wraith’s popping the clone right on top of your group. Markov will most likely have his ZEUS CANNON pulled out and doing consistent damage. When the Wraith pops her decoy, the gun WILL chain to her until she decides to move away. Your group just needs to be quick and pay attention, 'cause it doesn’t take much to move away from the chain. Overall, this can give your group a big advantage as to knowing where the Wraith is and will most likely result in damaging the real one.
Damage the real one enough and they’ll have no choice but to cancel their clone by warping or using their warp blast.
Off Topic From This Point On:
The reason why I’m putting this little tidbit is because once you know how to counter a Wraith’s decoy, you’ll need to learn next how to counter abduct (which I argue is THE strongest tool in Wraith’s arsenal) and the monster itself.
I feel as though the two strongest characters against a Wraith is Maggie and Markov, even against a decoy spammer. Normally I would say Abe for the trapper because stasis nades are very strong, but they don’t stop an abduction or warp blast from Wraith. Maggie’s traps on the other hand can at least delay a Wraith once it’s done warping and will keep Wraith held in place during an abduction. As a bonus, Maggie’s traps only react to the real Wraith. If a Wraith player can’t abduct and if you never get hit by decoy, they have no choice but to get in the face of your group. This is where Markov shines against Wraith.
Markov’s mines, I find, are a higher priority than doing damage with the lightning gun. The reason is obvious: when the Wraith’s in Melee range and doing Nova (aka going FULL HAM) you just need to kite the monster into your delicious mines. Now, if a Wraith player knows what they’re doing they’ll warp blast or abduct to destroy your mines. Markov simply needs to keep them spread apart so that one warp blast or abduct doesn’t destroy them all. The same thing can be said about Maggie’s traps. Also, I forgot to mention that abduct will shield Wraith from exploding mines. But, that doesn’t mean she’s immune to bullets during abducts transition/cast.
But even if you don’t have a Markov or Maggie on the team, you can still take on a Wraith. Knowledgeable hunters who know their class will always be much more valuable than having mines or auto~poons.