Boomshroom

Boomshrooms are grenade-shaped shrooms, and a member of the "3 Exploshrooms", along with the Punchshroom and Lavashroom. Each of these shrooms may be thrown to cause a destructive Explosion upon making contact with anything. Boomshrooms are the weakest of the trio, and encountered the earliest within the Tower, though may still be useful against the enemies in that area.

Explosion
At best, the Explosion will deal around 300 damage in a small AoE. The downside is that this damage will be reduced by Defense. The damage cannot be boosted by other Shrooms or Decals. While Boomshrooms may be able to take out a few barely-geared Screamers on the early floors, it will likely fail to do significant damage to more well-equipped opponents, like Haters. However, this Explosion will also knock down any enemies caught in it, no matter how strong they may be, leaving them lying on the ground for a few moments. Therefore, you can use the Exploshrooms to reliably knock down any enemy, leaving them incapacitated on the ground and vulnerable to attack from any of your other weapons.

Keep in mind that, while rare, it is possible for enemies to quickly jump back and recover from the explosion, if they were caught in it at a bad angle.

The explosion seems to count as Fire damage, as it will cook Raw Beasts (though Beasts like the Turtle and Pillbug still have to be made vulnerable to attacks first).

Eating the Boomshroom will deal -10 points of Durability damage to any Armor you have equipped, as well as damaging you and throwing you backwards.