From Halopedia, the Halo wiki
Suicide Jiralhanae are a specialised type of Jiralhanae employed by the Banished.
Suicide Jiralhanae are a variation of the standard Jiralhanae employed by the Banished. Upon death, they explode, damaging enemy forces in the radius.
Suicide Jiralhanae are assigned to a group of Suicide Grunts that appear in the Blitz multiplayer mode of Halo Wars 2 as a playable card for all Banished leaders. Unlike it's multiplayer counterpart, the Suicide Grunts are equipped with Plasma pistols
The Suicide Grunts are classed as anti-infantry, and performs well against infantry, vehicles and aircraft.