Aerial Felines. Fulminars are creatures composed of semisolid elemental matter and roughly shaped like large feline predators.

Cloud Giant Allies. Fulminars were either created or first summoned by powerful cloud giant sorcerers. They can also be found in the company of djinnis, silver dragons, and other creatures strongly connected to the element of air. It is unclear whether they have their own motives or are directed by a higher, elemental power.

Lightning-Fast Slayers. Thanks to their speed, stealth, and a strange magical ability to entrap creatures with shackles of lightning, fulminars are extremely versatile, serving as spies, assassins, and shock troops.

Elemental Nature. A fulminar doesn't require air, food, drink, or sleep.

Alternate Traits and Actions

Source ExpCod (Open Design)

The following changes allow GMs to alter a fulminar without modifying its challenge rating.

Forked Lightning. When the fulminar flies at least 10 feet, it creates a duplicate lightning form that potentially fools attackers. Until the beginning of its next turn, after it moves, attack rolls against it have disadvantage. If it is hit by an attack, this trait is disrupted until it moves again. The fulminar loses its Flyby and Essence of Lightning traits.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage and 7 (2d6) thunder damage, and the target must make a DC 16 Constitution saving throw. On a failure, the target is stunned until the end of the fulminar's next turn and deafened for 1 minute. On a success, the target is deafened until the end of the fulminar's next turn but isn't stunned. A deafened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The fulminar loses its bite attack and replaces its bite attack with the slam attack when taking a Multiattack action.