K’daai Fireborn
One of your more unique units, Fireborn are an offensive unit that’s surprisingly punchy, albeit in a somewhat squishy shell. First thing to notive is they’re Unbreakable and Unstable, so as soon as you lose combat, your W2 models will start dying quickly. And with T4, no armour and Regeneration (5+)/Warp-Spawned it’s not that hard to lose a few wounds in combat. At least they are Immune to Psychology.
But their value lies in the offensive anyway. They each have 3 flaming attacks WS4 S5 AP-1, that’s not bad. They also cause Fear and they have a Blazing Body on top. They are also quite fast at M6 and, since they don’t need any General/BSB bubble, are an excellent flanking unit.