Outside, go forward and jump off of the ledge, using the Sailcloth to soften your landing. Repeat this until you reach the bottom of the pit. Afterwards, the stone sealing away a very familiar beast shatters, unleashing the dreadful Imprisoned!
Boss: The Imprisoned
At the start of the battle, the boss’s main goal is to walk to the top of the pit and to the temple. This boss will stand upright – how is that important? Well, this boss has four toes per foot (one is in the back). Begin by slicing at the toes on one foot - three hits destroys a toe.
After removing the toes from one foot, the boss will move more slowly, but also summon shockwaves upon stepping down. Avoid these while you proceed to cut off the remaining foot’s toes.
Afterwards, the boss will fall over backwards. Once it does, run around and down the slope to the boss’s head and you’ll notice the stone pillar from earlier sticking out from its head. (I’d go crazy too if I had something like that in my head.) Anyhow, you’ll need to hit it with down-up vertical slices to damage the boss by driving the stone into the head.
After three such hits, the boss will stand back up, charge up the incline at a high speed, and continue walking at a slightly faster pace. Repeat the above processes until the boss is dead – three rounds of this, or nine hits to the head.
After the battle, go to the bottom of the pit once more and charge up your sword for a Skyward Strike. Hit the sealing stone to banish the creatue for somewhat longer.
Afterwards, you’ll end up back in the Sealed Temple.