I was wondering, can I target a spell with Disrupting Shoal not matching the target card? I understand it won't counter the spell, but can I legally do that play?
For example, Player A casts Dismember, and I cast Disrupting Shoal for 2, targeting Dismember. May I do that play? Or does it have to match?
Yes, you can target any spell with DS, regardless of what you choose for X. Because the targeting restriction is only "target spell", so any spell on the stack is legal (except DS itself). If the CMC doesn't match X when DS resolves, the targeted spell simply won't get countered.
Disrupting Shoal does not have a CMC targeting requirement. Instead, it checks if the targeted spells cost is equal to X when it resoves, and will counter it if it is.
To contrast, if it hypothetically said "Counter target spell with converted mana cost X", that would be a targeting requirement, and you would be unable to cast the Shoal targeting anything else.
Also, it is a good idea to check card rulings before posting questions. This can be done on this site, or at gatherer.wizards.com
This question is clearly answered in the card rulings.
For example, Player A casts Dismember, and I cast Disrupting Shoal for 2, targeting Dismember. May I do that play? Or does it have to match?
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)
To contrast, if it hypothetically said "Counter target spell with converted mana cost X", that would be a targeting requirement, and you would be unable to cast the Shoal targeting anything else.
Also, it is a good idea to check card rulings before posting questions. This can be done on this site, or at gatherer.wizards.com
This question is clearly answered in the card rulings.
A Dying Wish
To Rise Again
Chainer, Dementia Master
Muldrotha, the Gravetide
Atraxa, Praetors' Voice