I’d love to see someone from the Burning Legion as a commander. Someone like Mannoroth.
Starting with Big Manny himself, I’d make him a pretty straight forward.
He’d be a massive hero, spawning in at around a minute thirty or so, and would respawn with about half his health missing should he die.
His abilities would be cleave, a melee passive attack that does cone damage in front of him.
Howl of terror, an AoE debuff to attack damage and speed.
Enrage, gain air attack, attack damage and speed at the cost of defense, while also buffing his other spells while active.
And Reign of Chaos, drops down 4 (8 if enraged) abyssals, damaging and stunning units on impact.
The general design I have in mind for him is a sort of a more risky Kerrigan. His strong abilities and large health pool would allow him to be an early game workhorse, but without a self heal/shield, constantly solo throwing him into bad engagements would quickly cripple him.
If killed, his bio units will respawn back at his base at half of their build time, but the effect would have a 3 minute cooldown.
For the units, he’d have the Gan’arg. Maybe it could sacrifice health to boost movement speed/build speed.
Out of your starting barracks, you’d get three options of units.
Imps, a cheapo spammy ranged unit with little health. Comes out to 5 imps per 2 pop.
Fel-guards, the sturdy low-tier melee unit. Basically a zealot, but with higher health, damage, and mineral cost.
Mo’arg, the melee support. Summons turrets and gives defense buffs to nearby minions at the cost of energy. Has detection.
For his mechs, he’d get two kinds.
Infernal, the tanky melee construct with a passive AoE damage effect.
Infernal machine, the expensive but powerful siege vehicle. Can be upgraded to hit air.
Overall, I’m thinking he’d be the kind of commander type that would do well against ground comps, but would struggle in the early to mid game against air heavy comps.