It works particularly well for champs who already reduce the opponents combat power via Suppression or a similar effect - War Machine, Yondu, Darkhawk, IMIW, and most of all, Punisher 2099.
It's theoretically useful for all Techs, but if you're already decent at Power Control by Draining or Burning it, the effects aren't likely to be all that noticeable.
I find it's super helpful with silver centurion (yes I'm one of the weirdos that uses him) as it helps him stay close and keep lock on active for longer
It's pretty insane on a lot of Tech Champs. I'm not a Psycho-Man expert like you are, but I'd imagine he synergizes with it very well & boosts his fight control even further.
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It's theoretically useful for all Techs, but if you're already decent at Power Control by Draining or Burning it, the effects aren't likely to be all that noticeable.
It's just niche.
If you want to talk about useless, the scouting masteries....