If someone casts an instant, say lightning bolt, and then casts fork, targeting their lighting bolt, and I play wild ricochet, can I change the target of their fork to target my wild ricochet instead?
Or suppose I had two wild ricochets, and I target their fork first, then I target my own wild ricochet (A) with my second one (B)... can B make A target B?
What I'm getting at is, can I ever create an infinite loop (or arbitrarily large loop) of copy spells on the stack? Can one copy effect target another, and make it copy the initial one? Or will the Fork, in the example above, just fizzle on resolution since wild ricochet is now gone? I'm obviously confused, but I hope this is clear.
What, exactly, happens when you target a copy spell with another copy spell?
Help pull me from this infinite loop I'm stuck in!
You can change the target to the original spell however when the fork goes to resolve the wild ricochet will have already resolved and left the stack so the fork will fizzle and do nothing.
When Wild Ricochet resolves and targets Fork, you can change the target of Fork to any spell on the stack other than Fork, including Wild Ricochet itself (C.R. 115.5), since Wild Ricochet will still be on the stack as you do so (C.R. 608.2c, 608.2m, 608.2, 115.7d). And once you copy Fork this way, it will also have the same target as the original (C.R. 706.10), but Wild Ricochet allows you to change the copy's target to the original Fork or back to Lightning Bolt, or leave the target as it is (C.R. 115.7d). However, once Wild Ricochet leaves the stack, it will be an illegal target for Fork and/or the copy, so that when either spell resolves, it will fail to resolve if it targets the Wild Ricochet that left the stack (C.R. 608.2b).
(NOTE: I started writing the paragraph above before I saw comments 2 and 3. After I saw them, I wrote the following.)
This can indeed cause a loop as shown below.
1. Fork is on the stack.
2. You cast Wild Ricochet (WR1) targeting Fork.
3. Retaining priority, you cast another Wild Ricochet (WR2) targeting WR1 (C.R. 601.2i, 117.1a).
4. All players pass, then WR2 resolves (C.R. 117.4). You leave WR1's target as is, and you copy WR1 (the copy is WR3) and change the copy's target to WR1 (C.R. 608.2c, 115.7d, 706.10).
5. WR2 leaves the stack (C.R. 608.2m).
6. All players pass, then WR3 resolves (C.R. 117.4). You leave WR1's target as is, and you copy WR1 (the copy is WR4) and change the copy's target to WR1 (C.R. 608.2c, 115.7d, 706.10).
7. WR3 leaves the stack (C.R. 608.2m).
And so on.
This results in a fragmented loop within the meaning of C.R. 722.3, since notably, the "same game state" is reached multiple times. As a result, the active player (or the closest player in turn order to the active player who is involved in the loop, if the active player isn't involved) must make a different choice so the loop does not continue (in the loop above, it's you who must make that choice, since the loop involves only one player) (C.R. 722.3). (For sanctioned tournaments, see M.T.R. 4.4.)
EDIT (Dec. 24): Add rule citation; other edits.
EDIT (Oct. 15, 2019): Edited, including because some rules were renumbered with Core Set 2020.
EDIT (May 11, 2021; May 23, 2021): Some rules were was renumbered in the meantime.
Or suppose I had two wild ricochets, and I target their fork first, then I target my own wild ricochet (A) with my second one (B)... can B make A target B?
What I'm getting at is, can I ever create an infinite loop (or arbitrarily large loop) of copy spells on the stack? Can one copy effect target another, and make it copy the initial one? Or will the Fork, in the example above, just fizzle on resolution since wild ricochet is now gone? I'm obviously confused, but I hope this is clear.
What, exactly, happens when you target a copy spell with another copy spell?
Help pull me from this infinite loop I'm stuck in!
Wild Ricochet A is on the stack, then Wild Ricochet B changes its target (to whatever) and copies it...
So when B resolves, it puts a new copy of A on the stack, which lets it copy A again, right?
But I guess this goes nowhere, since it just keeps putting a copy of A on the stack over and over?
(NOTE: I started writing the paragraph above before I saw comments 2 and 3. After I saw them, I wrote the following.)
This can indeed cause a loop as shown below.
1. Fork is on the stack.
2. You cast Wild Ricochet (WR1) targeting Fork.
3. Retaining priority, you cast another Wild Ricochet (WR2) targeting WR1 (C.R. 601.2i, 117.1a).
4. All players pass, then WR2 resolves (C.R. 117.4). You leave WR1's target as is, and you copy WR1 (the copy is WR3) and change the copy's target to WR1 (C.R. 608.2c, 115.7d, 706.10).
5. WR2 leaves the stack (C.R. 608.2m).
6. All players pass, then WR3 resolves (C.R. 117.4). You leave WR1's target as is, and you copy WR1 (the copy is WR4) and change the copy's target to WR1 (C.R. 608.2c, 115.7d, 706.10).
7. WR3 leaves the stack (C.R. 608.2m).
And so on.
This results in a fragmented loop within the meaning of C.R. 722.3, since notably, the "same game state" is reached multiple times. As a result, the active player (or the closest player in turn order to the active player who is involved in the loop, if the active player isn't involved) must make a different choice so the loop does not continue (in the loop above, it's you who must make that choice, since the loop involves only one player) (C.R. 722.3). (For sanctioned tournaments, see M.T.R. 4.4.)
See also this thread.
EDIT (Dec. 24): Add rule citation; other edits.
EDIT (Oct. 15, 2019): Edited, including because some rules were renumbered with Core Set 2020.
EDIT (May 11, 2021; May 23, 2021): Some rules were was renumbered in the meantime.