A world with something to do.

Everyone who lived through the Sundering learned to breathe it. Reach level 3 — last long enough to be worth training.

The Covenant does not arm strangers. Cull 5 Slimes from the fields and the quartermaster will believe the Awakened came back a soldier.

The Horde does not feed the useless. Cull 5 Cowlings on the ridge and prove the Awakened came back with teeth.

Reach level 5 and the armoury opens to you. Steel is the first thing an Awakened is handed, and the last thing they ever put down.

The Abyss floods, and its water moves against the current. Whatever drowned down there did not stay drowned. Put 20 Abyss Wisps back under — and count how many of them are watching you while you do it.

The rot on the second floor has worked out which way is up. Burn 25 Gloomcaps before the spores reach the stair — and look at the light under their caps while they die. Fungus does not glow.

Embers drift the third floor, and the Emberthrone is a hundred leagues away. Either the mountain is bleeding into the Abyss or the Abyss is bleeding into the mountain. Kill 30 Cinder Motes. Nobody up here wants to say which.

The fourth floor is not haunted by anything that ever lived. No eyes. No face. Only a mouth. Kill 30 Maws — and understand what it means that whatever is making them has run out of things to imitate.

You asked what the Sunfallen were locked in WITH. Here is your answer: coiled at the bottom of the Abyss, wearing their gold. They did not entomb their kings — they entombed this, and buried the kings as the lock. Kill 40 Tomb Serpents and carry the crown back into the light.