And for the railgun type of thing, I think that would have to have a "tell" in front of it. This is common in a lot of games, when the boss gives you a signal of what attack he's about to launch, a second or two before does it, and you're supposed to read the signal and react. I tend not to do that sort of thing in my own games because that leads to a trial-and-error style of play where you're really relying on players to read those signals, and the player can only win after they do figure those signals out. My way is usually to omit the signals, but then instead to give a second or two for players to react to whatever just happened; a lot of game developers do this, too. A lot of the Mario games, for instance, are a mix of the two -- bullet bills give no warning but give you time to react, but many of the bosses have a tell before specific attacks.