Goblin Welder and Vedalken Shackles

[pandaman]

I have another one, I suspect that I may be wrong here.

I control Goblin Welder, 2 Sensei's Divining Tops, a Mox Opal, two Seat of the Synods and a Volcanic Island. I have two Grindstones in the graveyard.

My opponent controls a Vedalken Shackles, 2 Islands and 2 Tropical Islands. He had no artifacts in the graveyard.

It is my main phase.

I tap Goblin Welder and put its ability on the stack. In response, my opponent activates Vedalken Shackles targeting Gobin Welder. That resolve first, and my opponent becomes the controller of the Goblin Welder. Goblin Welder's ability resolves, and I go to choose Sensei's Divining Top, which is in play, and Grindstone, which is in the graveyard, to simultaneously sacrifice Sensei's Divining Top and return Grindstone to the battlefield.

My opponent says that I can't do that, because I don't control Goblin Welder and he chooses on resolution because he now controls Goblin Welder. I though that because I put the ability on the stack, when it resolved I chose the targets. But he said he chose the targets. Of course, being MWS, he didn't back it up with any reference to the rules, but called a noob and left. if you're reading this, please explain a rules dispute next time, or tell me the other person why you think they're wrong.

So when Goblin Welder's ability resolves, does he choose the targets or do I choose the targets? I now believe that I was wrong, and that he chooses the targets, but would like to know why.

And also, is choosing targets mandatory, so in any event if he chose he would have had to choose a Grindstone from my graveyard to return anyway?

[luma]

You choose targets as you activate the ability, not when it resolves. Even if you lose control of Goblin Welder, the ability still resolves with the original targets. Removing the source of the ability doesn't stop the ability from resolving. Your opponent was wrong here.

[cdr]

Also, taking control of the source of an ability that's on the stack will not change who controls the ability - the person who activated the ability still controls it. Even if Goblin Welder's ability didn't have targets, you'd still control the ability when it resolved and make any choices required.

[pandaman]

Thanks luma and cdr, appreciate your time.

[Zemoo]

by 'sac the top' do you mean using its 2nd abilty, or letting welder's ability resolve? because welder says exchange, not sacrifice, if the top isn't in play when welder resolves (i.e. you pop the top) then the exchange cannot happen because both targets of the exchange need to be exchanged or else nothing happens.

[cdr]

by 'sac the top' do you mean using its 2nd abilty, or letting welder's ability resolve? because welder says exchange, not sacrifice, if the top isn't in play when welder resolves (i.e. you pop the top) then the exchange cannot happen because both targets of the exchange need to be exchanged or else nothing happens.

It's pretty clear he meant the exchange with Goblin Welder.