Dr. Samhain summons "Mr. Kaboom", an otherworldly minion. The summoned entity doesn't actually have a name of its own. "Mr. Kaboom" is just a name Samhain chose for it. The entity can sneak into places and unleash an explosive force to which it's immune. Dr. Samnhain can summon other entities, but only one at a time. He must dismiss any present minion to summon another.
iceycakes originally conceived of the basic character, and I later adopted him from them and made him a novice mystic summoner superhero, a mix of a novice Dr. Strange and a starting pet trainer like in Pokemon or Digimon. Samhain has a lot to learn before he truly masters his art.
Artwork by the ever excellent aggrobadger.