Brass Beast

Antimagic Susceptibility. The beast is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the beast must succeed on a Constitution saving throw against the caster's spell save DC or fall unconscious for 1 minute.

Multiattack. The beast makes one horn attack and one spew fire attack(if available) on its turn.

Horn Attack. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage. 

Spew Fire. Ranged Weapon Attack: +1 to hit, range 20/40 ft., one target or two targets within 5 ft. of each other. Hit: 4 (1d6 + 1) fire damage. Can only be done when Flame Body is active.

Flame Body. This reaction is taken when the beast takes damage or comes into contact with fire. Any creature within 5 ft. of the beast makes a DC 13 Dexterity saving throw, taking 3 (1d6) fire damage on a failure and half that on a success. Objects that aren't being worn or carried within 5 ft. are set on fire. Furthermore, for one hour, Flame Body is considered active: Spew Fire is available and Horn Attack deals an additional 3 (1d6) fire damage. The beast emits bright light out to 15 ft. and dim light out another 15 ft. This reaction may not be taken again until Flame Body is no longer active.