The Boomas are a tribe of Uruks led by mysteriously old Uruks. Given their methods for warfare. This tribe specializes in explosives, and self-detonation.
Self-detonation is typically a last resort for Boomas. Except for disgraced or low status Uruks. These ones will blow themselves up as they hit the gates.
They have a council of 13 warchiefs instead of an Overlord.
Red Cult of Nyx 