Pyromancy Flames can be upgraded with titanite in the same fashion as regular weapons.
Their skill is a short range fire blast similar to the pyromancy Combustion from previous games. It scales with both Intelligence and Faith, similar to hexes from Dark Souls II. This is very different from previous Souls games, as in the past, pyromancy has had no stat requirements and thus was a favorite for pure physical builds.
Another flame was added in the Ashes of Ariandel expansion, which leaves harmful flame behind when casting pyromancies, and builds up a healing function every so many kills.