These two dungeons show up on the map as part of the third objective of the quest “fire in the sky” during the “for the king” campaign. They are both located in the Dropstone Badlands area of the map. Your entire party must be within the Dropstone Badlands area for each dungeon to start - just a single party member has to enter the dungeon and the rest will go in as well.
Each cave has five encounters - first three are normal battles and then a boss battle with a single level 10 ember demon for the fourth encounter. The fifth is the treasure room. The ember demons have 12 physical and 12 magic armor so you’ll need weapons that hit hard. They are immune to fire, lightening and stun. They use fire against you - in case you have any armor against fire or items that increase damage against fire enemies.