Activated abilities - of say Lin Sivvi, Defiant Hero - do use the stack. If you activate the first ability to search your library, that activated ability does go on the stack. Once everyone passes priority, it would resolve, allowing you to search your library for any Rebel and put it on the battlefield before shuffling your library. Please note that (in this particular example) you don't have to name the card you are searching for, so they have to respond before they know what is coming out - once you reveal it, it's too late.
Answers that your opponent can use to disrupt an activated ability are much rarer than things that answer spells (like Counterspell), but they do exist, which is part of why everyone has to pass priority before the ability can resolve. Here is a small list of things they could use:
Answers that your opponent can use to disrupt an activated ability are much rarer than things that answer spells (like Counterspell), but they do exist, which is part of why everyone has to pass priority before the ability can resolve. Here is a small list of things they could use:
Monoblue:
Disallow
Interdict
Nimble Obstructionist
Rimewind Cryomancer
Squelch
Stifle
Trickbind
Voidmage Husher
Other Colors:
Aven Mindcensor (doesn't counter, but does hurt)
Azorius Guildmage
Bind
Repudiate // Replicate
Voidslime
Somehow flash in Ob Nixilis, Unshackled or Stranglehold
2023 Average Peasant Cube|and Discussion
Because I have more decks than fit in a signature
Useful Resources:
MTGSalvation tags
EDHREC
ManabaseCrafter