Magma Mantle

This cracked black leather cloak is warm to the touch and faint ruddy light glows through the cracks. While wearing this cloak, you have resistance to cold damage. As an action, you can touch the brass clasp and speak the command word, which transforms the cloak into a flowing mantle of lava for 1 minute. During this time, you are unharmed by the intense heat, but any hostile creature within 5 feet of you that touches you or hits you with a melee attack takes 3d6 fire damage. In addition, for the duration, you suffer no damage from contact with lava, and you can burrow through lava at half your walking speed. The cloak can't be used this way again until the next dawn.