I am using a custom tileset, as you can see here:
Work in progress obviously.
And what I want the player to do, is to be able to jump down it, but not be able to go up it.
Notice my extremely well made diagram here:
As you can see by my perfectly drawn arrows, I would like the player to enter it from the top, jump, and land on the tile below the ledge.
Of course I could just do the direction thing and say it's not possible to enter it from the bottom, but that's not what I want.
I would like the player to actually jump.
I'm completely fine with setting up regions, that's not a problem at all.
You should always be able to do this, as long as you enter it from the right direction.
When the player jumps, a jumping SE should be played, and a shadow below the character should appear.