Charred Key in Baldur's Gate 3

Charred Key opens a heavy chest containing the two-handed staff Nature's Snare. Note that the sunuk itself is guarded by a fire trap.

But if you have the key, the trap won't work. But if you hack, be sure to activate it. The key should be found on a corpse in the same dungeon at coordinates X: -453, Y: -185. This dungeon can be accessed by jumping away from the cage with the goblin Sazza in the Druid Grove.

As for the chest, it is located at coordinates X: -425, Y: -200.