"Let’s begin with the Hellbat. It may not look like much when it’s just a Hellion, zipping around the battlefield spitting tiny streams of infernal plasma fuel. When it stands up however, this little car transforms into Hell on legs. With a cone-blasting flamethrower that obliterates any piece of flesh sorry enough to stand before it, the Hellbat is one of the most fearsome ground troops an enemy might ever stand toe-to-toe with."
Due to the good performance of the original hellion designed, the Terran Dominion opted to provide an upgrade to the vehicle. By combining the original vehicle’s speed, agility and firepower with the new battle mode’s strength, armor and durability, the hellbat is said to represent "the future of tactical assault technology." After the hellbat proved its worth on the battlefield, Dominion engineers quickly developed an upgrade kit to retrofit all previous generation hellions with the required components.
The modified hellions of junker gangs possessed the ability to transform into hellbats.
The hellbat template was built upon a heavily modified version of the hellion’s stock neosteel frame, which houses the complex set of servos, hydraulic systems, and robotic components that allow the mechanized walker to seamlessly transform into a vehicle and vice versa. The hellbat makes use of its predecessor’s base platform but adds state of the art robotics to the design. The most striking advancement comes in “battle mode,” which reconfigures the buggy into a mechanized walker.
The hellbat is equipped with a large variable burn engine powered by a variety of liquid or compressed fuels—essentially the big brother of the stock Hellion engine with much improved airflow. This upgraded engine provides enough newtons to compensate for the extra weight of the hellbat’s bulky systems. Like the hellion, it is also rumored to run on Scotty Bolger's Old No. 8 Whiskey.
"I don't care what they say, stay out of the way."
- A Dominion marine, in reaction to the hellbat's upgraded targeting system.(src)
With the advent of the hellbat, it became a necessity to replace the hellion’s scant plating. Dominion engineers used an experimental paristeel/bonded carbide weave (lighter and better insulated) to protect operator and machine from the incredibly high temperatures of the napalm spray. Additional heat-shielding, made from an expanding and re-forming material, was installed under the hellion’s chassis. It has proven very effective as a means of additional insulation, and it doubles as a solid riot shield.
In battle mode, the hellion’s infernal flamethrower transitions for immediate use, while a thick layer of heat shielding beneath the hellion’s chassis expands and re-forms to protect both robot and driver. The original incarnation of the infernal flamethrower was ineffective in close quarters, and installing a second weapon on an already taxed chassis proved unfeasible. To solve the issue, handy hellbat operators added a home-made, manually activated system, albeit useful only in walker mode as it reduces effective range, to pump polystyrene foam into the barrel of the infernal flamethrower prior to firing. The foam alters the density of the plasma fuel, which increases the flame’s intensity when ignited. This makes it very deadly against unarmored or lightly armored targets. This foam system is now standard issue in all Dominion hellbats.
After a friendly fire incident that killed 17 marines and sent 48 to the medbay with fourth-degree burns, the hellbat’s antiquated targeting system (a relic even by the antiquated hellion's standards) was replaced with a more sophisticated version. The new system provides better target acquisition, tracking functionality, and enhances the hellbat operator’s situational awareness. However, no targeting system can make up for the fact that the weapon sprays napalm. Troops are advised to steer clear of the line of fire.
The hellbat is produced directly from the factory with an armory requirement. The factory can also produce the hellion directly.
In comparison to the hellion, the hellbat's attack has a shorter, but stronger and wider flame. It is slower than its counterpart, but also tougher. While the hellion is mechanical, the hellbat is both biological and mechanical, and can both be repaired and healed.
Hellbats appear as mercenary units on the Braxis Holdout and Warhead Junction maps in Heroes of the Storm. On Braxis Holdout, they start out infested, but will revert to their natural state after being defeated. They fall into the game's "siege" category of mercenaries, attacking enemies with an area-of-effect flame attack.