so a while ago in MTGA i had the strangest thing happen to me
and i think my opponent tricked me on purpose with whatever this strange rule is
i played a noxious gearhulk with the effect targeting one of his creatures
in response he played a card that created 3 saprolings.
so after that card resolved the game asked me if i wanted to change targets(?!)
confused about what the game just asked (since in general you are not supposed to change targets after targets have been called wtf game?)
I clicked the cancel/no/whatever it said button, because i still wanted the same creature dead.
and then the noxious gearhulk didn't kill the creature. because somehow not changing my target was the same as nto chosing a target at all.
i was bamboozled!
so what rule caused this to happen? because the game acted as if i were allowed to change targets, which i obviously shouldn't have been able to, right?
Either it was a bug in the game or more likely it wasn't asking you to change targets but instead it was asking something like, 'do you want to destroy target creature'. Noxious Gearhulk's ability is a may ability so on resolution you get a choice of whether you want to destroy the targetted creature or not.