How to spawn a skeleton in the start room on every floor?

[pancelor]

I've got the mod framework working! I've been looking at https://github.com/Adikso/NecroDancerHeaders and making some wild guesses about how to do things, but I haven't made much progress beyond simple stuff like ignoring ice and coals, or making the bomb hotkey instead activate a Scroll of Need effect.

How would I write a mod that spawns a skeleton in the start room on every floor? This seems like it should hopefully be simple enough, but I'm not sure at the moment how to go about doing it.