Classic LitRPG x Powerful Fire Mage x World Covered in Water

Given an incredible fire class, Declan gets about three seconds to savor it before he's plunged into a drowned planet, a dungeon made out of another world that the System integrated, tested, and ultimately discarded.

But even if his fire can only burn at point blank range, it also allows him to propel himself. To keep himself from freezing in the abyssal depths. To power ancient engines left behind the planet's last inhabitants.

And when he gets out of this dungeon? Then things are going to burn.