Well, RPG Maker does use Ruby as a programming language, but I use a thing called the "Event System" which is technically like code. I'm not sure what you mean by "blocks" though, but it's definitely not nodes haha
Also yeah it is kind of complex, because using the event system makes it easier but also limiting. Also calling it "AI" is stretching it, because it's pretty basic due to how limiting the event system is. Honestly I'm pretty lucky that I'm able to make such complex items in a game engine that wasn't built for this complicated stuff. When it comes to the event system, you have to push the limits to get something good.
Usually when making the "AI", if I have to make something really complex, I'll have to think creatively to solve a problem with the "AI" or make my "event code" pretty long.
Here's an example. If the player chooses "yes" they get a message that says "HELLLOOOOOO", but if it's "no", then they get 9 potions.
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This is basically a snippet of the Opponents """AI""", if you can even call it that. The event system isn't necessarily made for enemies.
"[Eric]" is basically the player until you change his name.
the "Control varibales" are basically used for the Opponent to randomly pick items.
I'm gonna change some of this item picking "AI" though, so he'll/she'll be smarter to choose certain items. There is a conditional branch to detect the players items, so I plan for him/her to use steal cards straight away if he/she sees you have a healing syringe (he/she doesn't F around with those).
(if you look on the screen, you'll see "Common events." These are basically functions/methods)
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A snippet of when you choose to use items
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A snippet of the reloading ammo event.
sorry, I'm not the best at explaining stuff like this, haha.