The Boiling Wound is one of the Malignant Tunnels that was introduced during the Season of the Malignant and remains to be a repeatable dungeon.
It is one of the Malignant Tunnels that players can grind to obtain Caged Hearts through various methods, but they must brave the Malignant enemies first.
A powerful foe named Vorna will be met at the end, and you must slay this Malignant Werewolf to complete the Malignant Tunnel.
The Boiling Wound Location
The Boiling Wound can be found in the Frigid Expanse, which can be found to the very east of Kyovashad in the Fractured Peaks.
The closest Waypoints that you can teleport to are Yelesna (Gale Valley) or the Bear Tribe Refuge (Seat of the Heavens).
The Boiling Wound Objectives
1) Destroy the Malignant Corruption (3)
Upon entering The Boiling Wound, you will be starting in the Sweltering Passage, which is where you will need to destroy Malignant Corruptions.
These objects need to be attacked and monsters will attempt to defend them, including a Malignant Elite that will drop a Malignant Heart.
Once all the 3 Malignant Corruptions have been destroyed, you can proceed to the next area where a Malignant Werewolf awaits you.
2) Slay Vorna, Malignant Werewolf
After proceeding to the next area, which is the Sweltering Passage, you will need to slay Vorna, Malignant Werewolf.
Vorna is a Malignant Elite that is like other Werewolves but will be enhanced with certain buffs, including Lightning Damage.
3) (Optional) Capture the Malignant Heart
Once Vorna has been slain, a Malignant Heart will be dropped, and you can interact with it to spawn the Malignant Werewolf again and slay it to obtain a Caged Heart.
Vorna the Malignant Werewolf is not that difficult to beat but you should still watch out for the tethers that it sets up as well as the Charged Lightning that is released when you attack.
At the end of this Malignant Tunnel, you can find a Devious Overgrowth, which requires a Devious Malignant Invoker to summon a Malignant Elite.