Boom Fly (5e Creature)
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Small beast, unaligned
Boom. When a boom fly dies, it explodes. Creatures within 5 feet must make a DC 11 Constitution saving throw, taking 7 (2d6) thunder damage on a failed save, or half as much damage on a successful one.
Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 4 (1d6 + 1) piercing damage.
These massive insects have bloated bodies, huge beady eyes and small wings. They are filled with a volatile liquid that explodes on contact with the air. Chain reactions of boom flies are an uncommon dungeon hazard.
Variant: Red Boom Fly
Some species of boom fly are filled with pressurised caustic blood that sprays out when their body ruptures, rather than reacting explosively. For these creatures, replace the Boom feature with the following:
Red Boom. When a red boom fly dies, it sprays blood in a 10–foot sphere. Each creature in that area make a DC 11 Dexterity saving throw, taking 7 (2d6) acid damage on a failed save.