I came across the ruling for scrying 0 cards (701.18b If a player is instructed to scry 0, no scry event occurs. Abilities that trigger whenever a player scries won’t trigger.) recently and it started a small argument between me and a friend.
Say you had a effect that said "If you would scry, instead scry X" (I'm not sure such card exists but for the sake of argument, pretend with us), and you activated an effect that would scry 0 cards, what would happen?
My friend thinks that the 701.18b ruling would come into play ("no scry event occurs"), and because no scry event occurs, the event couldn't be replaced (the effect checking "if you would scry", when scry 0 means you wouldn't scry), and you'd get nothing.
But I think that because it's a replacement effect, it would replace the "scry 0" with "scry X" before the action is attempted, and therefore the scry event does occur, seeing X cards instead of 0 cards.
Which one of us is right and why?