In reply to Wehosh
Preflex is similar to one of my Semblances, so I'd like to say that being ambushed by one person would be nearly impossible. But being ambushed by a group is still very likely, since the people ambushing wouldn't be in the "immediate area", and ambush implies the surprise attack on a target, not the successful capture/kill/steal of a target. If the person doesn't consciously know that an attack is coming, the ambushers still have the element of surprise.
I feel like this needs more of a weakness side before adapting this to anything. (Needs balancing)
Parasite (I assume you meant) is kind of bad in many ways. Effecting an area where allies and enemies both are injured in order to give someone the ability to survive any long battle sounds horribly OP and needs to be worked on.
1. Draining allies with a passive ability is not good in any means, and even deadly.
2. The ability to feed off of the aura drained is way too strong in a group fight.
3. AOE passives should be toned down to the extent of minor abilities that keep happening. If you eat everything around you while simultaneously gaining strength, this leads to a very unbalanced Semblance that kills everything they meet.
4. I've said this before, Aura is a frail and very finite thing. Draining someone constantly would end the fight almost immediately if it had any noticeable effects on singular targets.
And lastly, I'd like to say that you should define "Passive". Qrow's Passive Semblance is always on, but a "Passive" Semblance could also be toggled into passiveness. And before anyone goes and makes a ton of Always-on Semblances, you should note that Qrow said his Semblance "Isn't like most." meaning it is highly irregular.
I have no problems with passive Semblances, but they need to be balanced enough to be able to function on a much smaller scale, considering the length involved in using such a thing. such as "occasionally making a table leg break." and "A building's already damaged support beam happens to crack under pressure." Not "Everyone around me takes constant damage while giving me extra strength" or "I can never be touched by a predictable target."
Sorry for the long review.