Aether vial question + True believer question

[GreenOne]

Question N.1
I got a vial with 1 counter and I tap it. The opponent plays Boomerang on the Vial. Vial goes in hand.

Do I still put a Lackey into play? I guess not beacuse there are no counters on vial.
Do I get to play an Ornithopter?

______________________

Question N.2
The I got a true believer in play. The opponent plays a thoughtseize. He obviously forgot that true believer was in play, nonetheless he played it. Does he have to target himself? Or he get to take the card back cause he declared he wanted to target me and he couldn't?

[Nihil Credo]

1) Vial will use Last Known Information, and allow you to put a CMC 1 creature card into play.

2) No, since the target is illegal his action (of declaring the Thoughtseize, targeting you) is illegal and simply gets reversed.

[Raindown]

Adding to this....If I respond by vialing in a True Believer say after Tendrils was cast on me will it 'counter'/cause tenrils to no longer have a valid target, including the storm'd spells?

[Taurelin]

I can just quote the rule for Storm:


502.30a Storm is a triggered ability that functions on the stack. “Storm” means “When you play this spell, put a copy of it onto the stack for each other spell that was played before it this turn. If the spell has any targets, you may choose new targets for any of the copies.”

That means you are not forced to choose new targets.

[cdr]

Adding to this....If I respond by vialing in a True Believer say after Tendrils was cast on me will it 'counter'/cause tenrils to no longer have a valid target, including the storm'd spells?

When the copies of Tendrils and then Tendrils resolve, their target will be illegal, and this will counter them.

The storm trigger allows your opponent to change the target of any or all of the storm copies, which (assuming the Tendrils targeted you) could mean himself or another player if in a multiplayer game.

Like Taurelin said your opponent is not, however, forced to change the target of the storm copies, even if the target is now illegal. If he does choose to change the target of a copy, it must be changed to a legal target.

Alternatively, you can wait until the storm trigger resolves and all copies go on the stack before Vialing the True Believer, avoiding all that target changing nonsense.