Ok, so fix for if you have your universal hunger set to low so your guys don't have to eat as much. If you wanna tame a grieve wraith faster, go to the great swamp, beat up a buncha' blood spiders, heal them up, bring them back home, TAME THEM, and then have them in the room on passive while you have your guys beat the grieve wraiths back down. So once the grieve wraith is unconscious again, dismiss a blood spider, it'll join the tech hunters, and then start consuming the grieve wraith. Don't worry too much, cause blood spiders will only eat their hunger til they either starve to death or regain consciousness.