Evolve

As the monster a time will come when you will have to fight the hunters head to head, your mission here is to incapacitate a hunter and make sure that hunter dies by bleeding out. I personally recomend going for the medic of the team first as they can revive teammates from a distance which can prevent a bleed out.

Once you have your target down, protect that target and prevent the other hunters from getting near to revive. Once your target bleeds out the achievement will pop.

This achievement doesn't seem to unlock in Custom Arena (like a couple of other achievements as well), so I set up Custom Defense. Kill the medic and try not to hit him/her while they are bleeding out as this might void the cheevo (not confirmed). And because it's defence, the A.I hunters are more interested in the Reactor than their dying comrade lol.
It should pop soon as medic dies

For the best chance, complete the first mastery level for the Kraken in order to unlock the Wraith.

Go to Solo -> Custom Match, choose Arena with "Extras" settings:
Difficulty Favour Monsters
Wildlife Population High
Strikes 2
Character Perks Off (this might be better on, but I finally got mine whilst off)
Battle Wins Required 1
Battle Duration Infinite
Starting Armour 100%
Starting Stage 3
Sudden Death Off

For skills, put 3 into abduction, 3 into decoy and 3 into supernova (not as important)

Sneak and sniff, getting behind a wall, when you see the medic dash slightly ahead of their team, use abduction on them to increase your distance and active supernova, use single hits of RT (but still fairly quickly) to incapacitate them without touching them when they go down. Now sit on the body and use decoy when available or supernova to scare the reimagining hunters away.

If you're still having trouble, try killing one or two others before trying (though I personally found this strategy less successful)