Those lava chests in Iron Keep can suck and die. Only one of them has anything worth getting--and sadly, that's the one that is the hardest. It contains a pyro spell (Firestorm, or something like it), and in order to get it, you have to do some clever footwork.
1) Get the cat fall ring and equip it. Also, equip your best fire resist gear. If you have the Pharros' Mask that you can get in the Iron King DLC, that thing constantly coats you in water so it helps a lot.
2) Climb up into the rafters. Remember how you can pull that lever and it sinks the platform down into the lava? Do that, and then use the new ladder that you can now access and go up.
3) Now there are a few pots filled with water up there. What you do is roll through them so you're coated in water. Immediately drop down from the edge onto the lava platform. You'll take damage from the fall, but the cat ring will help. Drink a flask real quick, and then move it to the chest. If you have any regen spells, you may wish to cast them before you drop.
The other chest by the pool of water just has a shield, but if you really want to get it, you roll around in that pool of water until you're soaked, and then book it, dropping off the ledge to save some time.
May I assume that you found the key in the Iron Key? It's on the body that was being burned in the very first room. Now see if you can figure out what that key unlocks, and then you'll be able to get the DLC key.
1) Get the cat fall ring and equip it. Also, equip your best fire resist gear. If you have the Pharros' Mask that you can get in the Iron King DLC, that thing constantly coats you in water so it helps a lot.
2) Climb up into the rafters. Remember how you can pull that lever and it sinks the platform down into the lava? Do that, and then use the new ladder that you can now access and go up.
3) Now there are a few pots filled with water up there. What you do is roll through them so you're coated in water. Immediately drop down from the edge onto the lava platform. You'll take damage from the fall, but the cat ring will help. Drink a flask real quick, and then move it to the chest. If you have any regen spells, you may wish to cast them before you drop.
The other chest by the pool of water just has a shield, but if you really want to get it, you roll around in that pool of water until you're soaked, and then book it, dropping off the ledge to save some time.
May I assume that you found the key in the Iron Key? It's on the body that was being burned in the very first room. Now see if you can figure out what that key unlocks, and then you'll be able to get the DLC key.