from FAQ:

"Put into Play" is a game mechanic that
bypasses all costs (including all gold penalties)
and play restrictions.

Darkstar's "instead of discard him put him into play" bypass the fact that a copy of darkstar could be into dead pile??? So Darkstar is never considered really dead?

thx in advance.

Gualdo said:

No. Play restrictions are things like "After you win a challenge" etc. Moreover "cannot" rule is more important I think (You also may not play or take control of a unique card if there is a copy of that card in your dead pile). However this rule don't use word "cannot" , so I'm curious what ktom will say.

Gualdo said:

Don't forget: "You cannot play, put into play or take control of a unique character that is already in play (except for duplicates) or in your dead pile" is not a play restriction . It is a rule . "Put into play" does not bypass any rules. Darkstar can, indeed, be killed - and if he is, his "put into play" effect on other copies is useless.

Rogue30 said:

However this rule don't use word "cannot" , so I'm curious what ktom will say.

"May not" vs. "cannot" is an awfully fine hair to split.

Thx for the clarification.

Another thing to keep in mind here:

"Put into play" only bypasses the play restrictions that the individual effect specifically says it does. So for example, if I have the new "Fear of Winter" plot out (Each player cannot play or put into play more than 1 card from his or her hand until you reveal a new plot card.) and you have already played a card, when Darkstar is discarded from your hand during an Intrigue challenge, you could not put him into play (and he would be discarded). He does not specifically bypass the restriction placed on you by the plot, so it kicks in.

So that's another way to look at the original question. Since Darkstar's "put into play" ability does not specifically let you ignore the rules for unique/dead pile restriction, he is still subject to it.