Duergar's Flamejet

This long cylindrical tube has a perpetual flame burning at the far opening. It sloshes with a
strange gel-like fluid.
As an action, the wielder of the flamejet can fire
a gout of flame in a 100 ft. line, 5 ft. wide. Every creature in the line must make a DC 16 Dexterity saving throw, taking 4d8 fire damage on a failed
save, or half as much on a successful one.
The device has 5 shots worth of flame gel left.