I can kinda see a bit of a balance issue. The issue being, if you have enough of them with a rainbow deck, they will practically never have a deck and you have a hand full of usable cards. Even without the rainbow, it could be abused to take away cards to a point of extreme obnoxiousness and spammability.
If you abuse it without a rainbow or mindgate or something to use the cards you get, then abusing it gets both of you nowhere, as both your hands will be clogged up. Also think of Nightmare, which gets to a similar situation:
Your hand gets filled with something you can't play = dead hand.
Your cards get stolen by H&M = dead hand.
Another similar situation is Black Hole; if spammed, then you - might - have no quanta, which = dead hand.
If your target's hand has card he/she/AI would want to keep for later or something, and suddenly their entire hand is gone due to a flock of these, I think it is a different case. Nightmare gives copies, but the original is still here. This card takes cards directly from the opponents hands.
In terms of Black Hole or any Pillar Killers, those are specialized decks here. This is something that could fit in a slightly modified deck. If you still don't want the card, you just discard the crap to free up your hand. Worst case scenario, you get a hand full of Ghosts of the Past.
