What makes that boy special? I mean 2d12 club is nice, but why the boy and not one of Minotaurs for instance?
Allow me to demonstrate, Mirkon soloing the Goblin Camp courtyard in 6 minutes:
Tiefling kids can't enter combat. So if there is combat going on(preventing NPC auto-heal) they can run around in real time and make unlimited attacks.
Add the club to that, and even though he misses a lot more than a minotaur, they can do damage fast enough to kill a large fraction of NPCs in the game, even if there's no combat nearby and NPCs auto-heal.
Arabella works too, but Mirkon auto-resurrects under certain conditions, so it's harder for him to get killed accidentally.
