This skip was found by me. Using a Dragonscale Expedition Pillow (Soft Purple Pillow / Small Triangular Pillow / Skinny Reliquary Pillow), you can get through the invisible wall and go from the 2nd boss directly to the last.

Note that if you defeat the 1st boss before they fully arrive, you will actually softlock the dungeon as the gates won't open.

Watch out, it's really easy to pull extra mobs which can slow you down massively. While in combat, you can't activate the Oddly-Shaped Horn, Gunshoes, or place any of the Pillows, so dodging all mobs is crucial. Using Shadowmeld at the right time is also key.

Items used:

• Before entering: Fried Bonefish, Charged Phial of Alacrity, Pep-In-Your-Step
• During run: Oddly-Shaped Horn (temporary mount), Soft Purple Pillow, Gunshoes, Quickwick Candlestick