It's actually really simple "If x, then Y" stuff. I haven't really dug too much into it, but the Invasion thing stemmed from the most basic setup:

if (Phaeton = Destroyed) {

sendmessage(Alpha) ;
do {

InvisibleBlock("Alpha");

ReceiveMessage;

} Move (X/Y:30,0);
}

*I don't code lol

If Phaeton is destroyed > Invisible block moves 30 units up.
Since the Anti-spawn Zone sits on top of the block, it gets moved up too (Normal physics). Phaeton being destroyed was set to "Send Message" to all of "Alpha", and all of the Invisible blocks were set to move when "Alpha" channel received a message.

That's just one script. Each object can apparently hold eight different scripts, with different parameters.

: Almost seems like they're intrinsic components to the base game and not something a fan
: could casually design over the course of a weekend.

This video is my third ever attempt at scripting in Halo 5. The first two were done out of curiosity (and left as easter eggs) on my Combine map. If I can figure it out, I'm sure you can. Scripting is going to be huge once people start figuring it out and applying it.