Duress and Deed/G. Welder questions

[new sheep]

1. Do I have to choose a card to discard when I play Duress? Offcourse if there is non creature non land card in my opp's hand.



2. My opp have Pernicius Deed, Phyrexian Collosus and Mox Ruby in play. He go to declare attacers step so I decided to eat Mox with my Gorilla Shaman. He sac Deed for 1 in response and in response I tap Goblin Welder to excange Mox for Collosus(there was no other artifacts in his grave except Mox on table). Whill I excange DC with Mox in this scenerio?

[Jebus]

1.  Yes.  If there is a non-creature, non-land card in their hand you must pick one for them to discard.

2.  I don't understand your question.  It sounds like the mox isn't even in his graveyard yet, so you wouldn't be able to weld anything.

[Frappie]

Lets spread this out so you can see how the stack works.

Player X (X is you)
Player Y (Y is your opponent)

Player Y declares DS colossus as an attacker.
Player X activates Gorilla Shaman targeting Mox Ruby.
Player Y Activates Pernicious Deed (where the ammount paid is one)

Ok at this point with the abbilities on the stack nothing is in the graveyard as a result. if the Deed resolves and places the mox in the yard then your goblin welder is also in the yard and that means that there is no chance you can activate a dead welder. However if there is already a mox in the yard then you can activate the welder targeting the mox and the colossus.

[Limbo]

Frappie is correct, but there may be a solution to your problems. You said you wanted to eat their mox with a shaman. If you happen to have another free mana, you can activate the shaman again to eat the mox. The stack will look like this at that point:

Top
Shaman eats red mox
Deed activation
Shaman eats red mox
Bottom

The stack resolves one item at a time, so when the first item resolves, there is indeed a situation with a mox in the graveyard and a DC in play, which would enable you to weld out the DC. Remember that your shaman activation for the red mox that is still on the stack does not recognize the mox as the mox it was targeting. In this example the deed will blow it up though, but could be important in another situation.

And your shaman and welder still die as a result of the deed...

Hope this helps, Leon