When this card first came out, I thought it was severely broken. Played three (3) copies in almost every Justice deck I ran. Now, I think I understand how it's balanced, at least somewhat.
After some time with it, I'm learning that the cost is a pretty decent hinderance, especially early game. It does set you back a good bit if played really early. It's made to be a persistent tick, but has no burst, which you need sometimes. Laying it down turn 1-2 is your best bet but is it always the best play on turn one? Would a better piece of your kit work better for you in the long run?
I think it sits best in a deck that can pump out a lot of resources, or a deck that can also thwart in Alter-Ego (She-Hulk). The card is still valuable in that one (1) thwart per turn is still great, and then killing a minion eventually can be game saving. It just takes 4+ turns to see value, and for some Justice decks, that may be too long.