In a game of commander, I would like to use Scion of the Ur-Dragon as my formal/official commander, and use Scion’s activated ability to turn Scion into a copy of a different creature— my “hidden commander.” Scion’s activated ability allows its controller to search their library for a Dragon permanent card and put it into their graveyard. When they do, Scion of the Ur-Dragon becomes a copy of that card until end of turn. I would like to do this turn after turn with the same creature. Normally, this wouldn’t be possible because you have to place the card representing the creature that you want Scion to become a copy of in your graveyard. I would like to know if the following sequence is possible, or if it can be adjusted to make it possible:
Let's assume that Maskwood Nexus is in play, allowing me to turn Scion’s into a copy of any creature in my library, not just dragons. (Alternatively, I could use Arcane Adaptation or Conspiracy, naming “dragon” as the chosen creature type).
I activate Scion’s ability placing my hidden commander (let’s say it’s Skithiryx, the Blight Dragon) into my graveyard, and I hold priority. I respond to that activation by activating Scion’s ability a second time. Now there are two activations on the stack. This time I place either Ulamog, the Infinite Gyre or Kozilek, Butcher of Truth into my graveyard. (Both of these cards say, “When <this card> is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.”)
Resolve the second activation, turning Scion into a copy of Ulamog or Kozilek. Resolve the first Scion activation, turning Scion into a copy of Skithiryx.
Obviously, the intention here is that as soon as Ulamog or Kozilek are placed in the graveyard, the graveyard gets shuffled into my library, putting my “hidden commander” back into the library so that I can tutor for it again next turn. That's my only reason for using Scion's ability to turn him into an Eldrazi creature. Will this work as I’ve described it, or can it be tweaked to work?
You don't really need to "hold" priority. Also, you don't put the card in the graveyard until the ability starts resolving. Which means there isn't a good way to sequence what you are trying to do since if you turn it into a Kozilek first, the trigger goes on the stack before the other ability resolves leaving Skithiryx in the graveyard. If you do Skithiryx first then Kozilek can shuffle it away but then you "only" have a Kozilek.
You would end up needing something else. Something like Wheel of Sun and Moon would work since it does reveal the card and the effect doesn't actually care if it makes it to the yard; just that you searched it up and the game can see what it is.
Also, please don't type what the card's text is, even if it is paraphrased: that is what the card tags are for Having to skim/skip over the card text makes it tough to follow along with the actual question.
What if I use Scion of the Ur-Dragon's ability to turn Scion into a copy of Skithiryx, the Blight Dragon on one turn? Then, on the next turn, I follow the procedure that I described above? (At the beginning of this turn, Skithiryx is already in my graveyard.)
When the second activation (as described above) starts to resolve, Ulamog, the Infinite Gyre is placed in my graveyard. As a result, do the cards in my graveyard get shuffled into my library immediately? You said that Skithiryx isn't placed into my graveyard until the first activation starts to resolve. By the time that the first activation starts to resolve, is Skithiryx still in my graveyard, or is he in my library (waiting to be moved into my graveyard)?
Scion of the Ur-dragon turning into a copy of another creature is conditional. It would seem that the ability can't fully resolve unless I put a creature card in my graveyard, and the first activation of Scion's ability can't resolve until the second activation has resolved. When Ulamog, the Infinite Gyre is placed in my graveyard, do the cards in the graveyard get shuffled into the library immediately? Or can Scion's first activation completely resolve while Skithiryx is still in the graveyard?
If Skithiryx is already in the yard you can activate Scion twice like you said. The first activation resolves and you get Ulamog. Scion becomes an Ulamog and Ulamog's trigger goes onto the stack to shuffle your graveyard into your library. This resolves before the other activation of Scion resolves. Then, when the waiting activation resolves, you can find Skithiryx since it is now in your library. You will put it into your graveyard and Scion becomes Skithiryx. By fragmenting things this way you can get the dragons in your yard back on the next turn to re-use them. You just can's do it all in one turn so there will be some time where the dragons will sit in your graveyard before you use Scion on another turn to get Ulamog.
Basically, you can just activate Scion on your turn to turn it into Skithiryx. On the next turn (your opponent's turn if you want), you can get Ulamog to shuffle it back in. Then repeat the process on your next turn.
Let's assume that Maskwood Nexus is in play, allowing me to turn Scion’s into a copy of any creature in my library, not just dragons. (Alternatively, I could use Arcane Adaptation or Conspiracy, naming “dragon” as the chosen creature type).
I activate Scion’s ability placing my hidden commander (let’s say it’s Skithiryx, the Blight Dragon) into my graveyard, and I hold priority. I respond to that activation by activating Scion’s ability a second time. Now there are two activations on the stack. This time I place either Ulamog, the Infinite Gyre or Kozilek, Butcher of Truth into my graveyard. (Both of these cards say, “When <this card> is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.”)
Resolve the second activation, turning Scion into a copy of Ulamog or Kozilek. Resolve the first Scion activation, turning Scion into a copy of Skithiryx.
Obviously, the intention here is that as soon as Ulamog or Kozilek are placed in the graveyard, the graveyard gets shuffled into my library, putting my “hidden commander” back into the library so that I can tutor for it again next turn. That's my only reason for using Scion's ability to turn him into an Eldrazi creature. Will this work as I’ve described it, or can it be tweaked to work?
You would end up needing something else. Something like Wheel of Sun and Moon would work since it does reveal the card and the effect doesn't actually care if it makes it to the yard; just that you searched it up and the game can see what it is.
Also, please don't type what the card's text is, even if it is paraphrased: that is what the card tags are for Having to skim/skip over the card text makes it tough to follow along with the actual question.
When the second activation (as described above) starts to resolve, Ulamog, the Infinite Gyre is placed in my graveyard. As a result, do the cards in my graveyard get shuffled into my library immediately? You said that Skithiryx isn't placed into my graveyard until the first activation starts to resolve. By the time that the first activation starts to resolve, is Skithiryx still in my graveyard, or is he in my library (waiting to be moved into my graveyard)?
Scion of the Ur-dragon turning into a copy of another creature is conditional. It would seem that the ability can't fully resolve unless I put a creature card in my graveyard, and the first activation of Scion's ability can't resolve until the second activation has resolved. When Ulamog, the Infinite Gyre is placed in my graveyard, do the cards in the graveyard get shuffled into the library immediately? Or can Scion's first activation completely resolve while Skithiryx is still in the graveyard?
Basically, you can just activate Scion on your turn to turn it into Skithiryx. On the next turn (your opponent's turn if you want), you can get Ulamog to shuffle it back in. Then repeat the process on your next turn.