I got the thing from kingdom edge, what now? (major spoilers)

[God Snek]

I'm being vague on purpose for title but... I just defeated Hornet (good god she was challenging. Her ♥♥♥♥♥♥♥... Tinsel spike things pissed me off) and got the kings mark. I know there's multiple endings and i plan on getting all of them so should i go to the door in the basin and then i get an ending...? (I want to just make sure i can get all of them and not ah ♥♥♥♥ up)

[Mister Veeg]

you can go visit the abyss if you want, there's some good powerups down there.

as far as ending stuff goes, there's a good bit of groundwork to do outside the abyss to actually get them. You'll want to do the normal ending first (you can't particularly blunder your way into the other endings, so don't worry overmuch)

[God Snek]

Originally posted by Space King Veeg:

you can go visit the abyss if you want, there's some good powerups down there.

as far as ending stuff goes, there's a good bit of groundwork to do outside the abyss to actually get them. You'll want to do the normal ending first (you can't particularly blunder your way into the other endings, so don't worry overmuch)

So the abyss is the locked door?

Oh, do i need to deal with the dreamers before i get the normal one? (Iv'e only defeated the beast)

[Nomenanza]

The King's mark will allow you to go through the door in the lowermost section of the Ancient Basin.
Don't worry about endings. Only 2 respectively exclusive items change the endings in the game (not having any of them in the final fight is the default ending). Going through the door will not change anything aside from giving you a new cool zone to explore and a new set of powers to acquire.
The abilities you get in that area are so good, I would recommend going there straight after you beat Hornet the second time.