Here's another one that seems to be semi broken right now on my end. /initiate_wave 0 1 -1, the first parameter is wave level, the second is time before it shows up (in seconds), the third is the faction it is being spawned for.
I'm sure there's a way to rig this to get a working spawning system again but it does come in handy if you want to send waves at yourself.
In any event hopefully the devs fix this soon.