The Harvog Assault Bot is an Illuminate direct-fire land unit, and the only non-experimental illuminate land unit not capable of hovering on water. It can be upgraded with shields and Anti-Air capabilities, making it a versatile combat unit.
Notably, both the weapons it uses are Seraphim weapons from Supreme Commander: Forged Alliance. The Aire-au Bolters were found on the Ilshavoh and Othuum, and the Shleo AA Autogun was the standard Seraphim light AA. The Aeon light AA tech is the Sonic Pulse Battery... though the Aeon lacked a direct counterpart to the Aire-au Bolters except perhaps the Quantum Autogun formerly on the Blaze Tier 2 Hover Tank.
When used to jump into the middle of a base or out of combat, the teleport ability can often confuse enemy commanders and give you a short period of time where you are receiving minimal fire. This can give you a head start on taking out a target or retreating from battle.
It receives the most benefit of any land unit from research. The anti-air upgrade is a good first choice, followed by veterancy or damage upgrades.
Don't be fooled into thinking that the Anti-Air weapon is a replacement for dedicated anti air like the Crahdow, its low DPS means that it's only useful for swatting small numbers of pesky aircraft or to compliment other forms of Anti-Air.
Small groups of Harvogs are relatively ineffective, swarm them for maximum effect.
While defensive upgrades are helpful, Harvogs are assault units and are designed to deal damage rather than take it. Thus, consider a high-speed deployment mechanism such as transports or the Space Temple.
Harvogs cannot float on water, thus making this unit a poor choice if you wish to exploit the Illuminate's hover advantage. Don't forget however that Harvogs can potentially teleport across with a special ability once the correct research is made.
Unlike it's slowfiring, long range, reclaiming predesscor, the Harbinger Mark IV, the Harvog does not work well in typical combat on it's own, easily overwhelmed by Loyalists or Rockheads. They work best with guerrila tactics or supported by Yenzoos. However both units are quite good at escorting or destroying experimentals.