Hi it does get pretty hectic at that stage as a rather large Knight always spawns right smack in the middle of the entrance to the vault room, just when you usually enter and change over the heart. There will be a wall over either trees or rocks but as your view is better when you enter the antechamber towards the tree side, it should be easier to know which one is blocked...only left or right. Either way if you go left to rocks, stay close to the wall on your left then basically do a hard u-turn into the small tunnel, careful of the phalanx waiting, run through across the next room into the final tunnel, again a waiting phalanx, then on to the drop down hole. You do the exact opposite for trees, turning right, hugging the right wall... It’s a mirror image. Then it’s usually a heart change over before you jump down the hole as you don’t want to be teleported mid drop so just wait at the top if you are not alone. Jump down then proceed up the small staircase, dunk the heart, collect loot 😃