i cant upload levels

The achiviment says to fire a cannon from a cannon, but I don't know how to make a cannon fire in the editor

any level makers able to help me out with boss health bar stuff, i want to make it so the boss health bar only shows up after a certain point, like when a trigger is activated or something anyone know how to help me out with this?

Some of the bosses in the campaign randomly pick their attacks, I want to do this in my levels but have no idea how they did it. HELP.

- Bigger rooms, basically have no limit on how big room can be, Yes, it may introduce lag, but a) it's up to the level creators to optimize their levels, b) sometimes you may actually want some lag, such as if you're making a bullet hell level so that you have time to react - Kill player event command so that we can create kill zones with something other than enemies/apples/spikes if those don't fit the level aesthetically (or e.g. making some props that realistically would kill the player, such as the cam...