Firedrakes are magical creatures that emit a trail of sparks behind them when they fly (CG).
Circus Arcanus had a cage of Firedrakes. They caused the circus tent to catch on fire when Credence busted open their cage and they escaped (CG).
"Firedrake" has several pertinent real-world definitions. It can refer to a wyvern (Wikipedia), a dragon, a comet, a will-o'-the-wisp, someone "whose work involves fire, as a fireman, furnace keeper, or alchemist's assistant", a person who likes to fight, or a type of firework (Oxford English Dictionary).