Devotion change color question

[Destore117]

Ok say my opponent plays a card like {Gray merchant of asphodel} or {Fanatic of Mogis}
Would I be able to use {Quicken} + {Trait Doctoring} to change devotion to ~~color~~ to a different color say one they don't have in essence making their card do 0 damage/life loss?

[Agrus Kos, Enforcer of Truth]

Ok say my opponent plays a card like {Gray merchant of asphodel} or {Fanatic of Mogis}
Would I be able to use {Quicken} + {Trait Doctoring} to change devotion to ~~color~~ to a different color say one they don't have in essence making their card do 0 damage/life loss?

No, you can not. When {Gray Merchant of Asphodel} ETBs, his ability goes on the stack. Even if you respond with {Quicken}+{Trait Doctoring}, all you have achieved is changing the text on the card, not the ability on the stack. {Sleight of Mind} achieves the desired effect though, because it can change the wording of the ability.

[Destore117]

Ok say my opponent plays a card like {Gray merchant of asphodel} or {Fanatic of Mogis}
Would I be able to use {Quicken} + {Trait Doctoring} to change devotion to ~~color~~ to a different color say one they don't have in essence making their card do 0 damage/life loss?

No, you can not. When {Gray Merchant of Asphodel} ETBs, his ability goes on the stack. Even if you respond with {Quicken}+{Trait Doctoring}, all you have achieved is changing the text on the card, not the ability on the stack. {Sleight of Mind} achieves the desired effect though, because it can change the wording of the ability.

So I'd have to change the text of the spell on the stack?

[Agrus Kos, Enforcer of Truth]

Ok say my opponent plays a card like {Gray merchant of asphodel} or {Fanatic of Mogis}
Would I be able to use {Quicken} + {Trait Doctoring} to change devotion to ~~color~~ to a different color say one they don't have in essence making their card do 0 damage/life loss?

No, you can not. When {Gray Merchant of Asphodel} ETBs, his ability goes on the stack. Even if you respond with {Quicken}+{Trait Doctoring}, all you have achieved is changing the text on the card, not the ability on the stack. {Sleight of Mind} achieves the desired effect though, because it can change the wording of the ability.

So I'd have to change the text of the spell on the stack?

Yes. Technically the ability on the stack, but yes.

[Destore117]

Oh. Ok. I get it now. So I'm changing the spell so that when he enters and becomes a creature permanent his ability reads lose/deal damage equal to devotion to •changed color•
Thank you.

[Remillo]

Agrus has it correct, here.  Now, if you were to target Grey Merchant on the stack with {Sleight of Mind} or {Glamerdye}, the color change will continue to effect the permanent the spell becomes.

Resolved

[sithantic]

Would you not be able to do this in response to Gary being cast? While he's still on the stack, cast Quicken + Trait Doctoring? Even with Gary on the stack, he's still a permanent, right?

[Agrus Kos, Enforcer of Truth]

Would you not be able to do this in response to Gary being cast? While he's still on the stack, cast Quicken + Trait Doctoring? Even with Gary on the stack, he's still a permanent, right?

No, he is not a permanent on the stack, just a spell.