Boss room help...

Simple: Just put a shutter door in the boss room.

Sure. Just use a shutter door. They are programmed to open once the enemies are defeated if you don't have any other screen flags enabled.

EDIT: Ah, posted at the same time as LinkMaster 😊

This is weird. I set my boss in my first dungeon to make the triforce appear on the floof behind him when he's defeated. Alls well until I grab the triforce, then for some reason I get sent to an empty item room, instead of being sent to the outside of the labrynth. When I leave the room it just sets me in the boss roon again. any clue what I'm doing wrong?

According to Alphadawg's tutorial*, you have to set a side warp (entrance/exit) and a tile warp (insta-warp with zap effects) in order for the Triforce to warp you out properly.

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*This is what Alphadawg's tutorial said, but I'm not sure if there is a more condensed way of doing so. I read it such a long time ago, and it definitely works.

You can actually just set a side warp for it to work

I don't know but I found AlphaDawgs tutorial (even though it's a rather old one) very helpful on the Triforce room.. worked fine for me.
Just try his part on the Triforce room.. as someone else stated, you are (according to Alpha) supposed to set a tile warp and a side warp for it to teleport you out correctly.

I too used to have this problem. I believe that it's because he didn't make the Triforce have a specific room, and just made it appear when the Boss was killed. Or, at least that was what set off the glitch for me.