Multiattack

Two Wrecking Maul or Fire Blast attacks.

Wrecking Maul

Melee Weapon Attack: +5 to hit, 5 ft., one target, 10 (2d6+3) bludgeoning damage + 3 (1d6) fire. The target must make DC 13 Str save or be pushed up to 15 ft. away from the firecracker and knocked prone.

Fire Blast

Ranged Spell Attack: +4 to hit, 60 ft., one target, 12 (3d6+2) fire.

Combustion Wave (Recharge 5-6)

The firecracker slams its massive hammer into the ground battering itself and its foes with fiery shockwave. Each creature within 20' of the firecracker including itself must make a DC 13 Con save taking 10 (3d6) fire and 10 (3d6) thunder on a failed save or half damage if made. Creatures behind cover have advantage on the save.