Magical fire, and all other magical elements, only exists while it is being fed mana. Once the source of mana is depleted, the fire ceases to exist. Therefore, the heat produced by the flames only last while they are being fed by mana much like real fire needs fuel to burn.
That was the reason many fire spells, though could burn gravely a person, didn't cause widespread fires. Because, once the mana that fed the spell vanished, the heat it created was quickly dispersed.
However, even magical fire could create enough heat to ignite objects if the flame was kept live with mana for long enough.
That was what Ffyr's flame-throwing spell was doing around them. It ignited the wood of the furniture, the papers of the documents and even the fur of the Gnoles. It didn't take long for the first floor to be covered in fire and for the sprinklers to activate flooding the ground with water.
