How to make attack of main boss in air to show that boss is on that level

[Silverthorn]

What I'd do is to create a dummy-file (or modify some existing char such as template or so) where you add frames that spawn the stuff you would like to have. In order that the attacks appear again and again, you might want to consider putting this into a weapon, though, as you will otherwise have to kill the spawning-object to proceed to the next phase.

Also, I wouldn't recommend to use a ratio of 50. Imagine you play (even though it's unlikely, it's still possible) with 8 players in total. This would mean that the object is being created 8x50=400 times. I have often encountered the exe crashing if there are over 380-ish objects in-game simultaneously.