While this card is in play, target card is now controlled by both creatures.
Don't you mean "controlled by both players"? o.O
This looks like a very interesting mechanic, not sure how balanced it is. It can't target immortal creatures or protected permanents, correct?
When you say it attacks both players, do you mean one after the other, or both at the same time each turn?
Derp. Text fixed.
Yes, it cannot target things that cannot be targeted.
It attacks as if it were one of your own. So it would attack when you end your turn.
If I target a pillar what happens? Does it affect the whole stack?
If I target my opponent's SoP, can I remove the shard?
It seems a bit situational, as you'd normally not have the quanta to play the abilities. So I think the most important effect to take into account, for balancing, is the PU-like effect that affects both creatures and permanents (maybe take the cost of PU and add 1 quanta?).
It will only affect one. If the stack is targeted by EQ or any other PC, Hijack is destroyed.
Yes, you can remove SoP in this manner.
I have costing 6 since although it is essentially both a PU and Steal, it is essentially easier to get around due to PC.
you do mean both players I assume. Anyways for most things steal is a better card for permanents. for creatures this is an odd choice. when exactly would you want to use this card?
One thing I can see this used with is Singularity, since it will attack either player and isn't getting rid of it. It will also make creatures unable to be Immolated or Pult'd, as well as being used for Chimera. It can be used as a way to flood both fields with Malignant Cells. Can technically be used to bump up the effects of Empathetic Bond and Hope. It is an AI deterrent as it will count that targeted card still as its own. Et cetera.