Slitherine

What does the "Abandon" command actually do when I occupy an enemy province? It just states that it will leave the region to its own devices, but not much else.

Thanks!

If you own a region which you think won't contribute anything useful, but you have an army that you move out, you can abandon it.
It could be region which others own over half of the province it belongs too, so you would get more decadence as its not part of your province.
It could be that you want to create a new minor. If you use the regional decision Liberate Region you might get a client state instead.
You have to leave the province while the army has the order abandon.

Oh, so it is the same as Liberate Region, except that the decision increases the odds of installing a client barbarian tribe?

I love to use Liberate Region to create rump countries and dismantle bigger Kingdoms (like the Diadochi kingdoms). For this I usually hoard as many Liberate Regions as possible to use it in border province.