Can you block, stop, or otherwise counter an activated ability? Or is it pretty much a given that once it's activated, there's no stopping what's gonna happen. Like Anaba Shaman, Benalish Trapper, etc.... I read somewhere that the effect of some like the ability to search for a rebel or whatever would still happen even if you were to kill the summoner after the ability was activated. So, I'm curious if you could prevent any activated ability from following through to the eventual conclusion.