Drilldozer

The Drilldozer (also known as the Dozer for short, and affectionately nicknamed "Doretta" by the Dwarves) is a large, automated mining vehicle deployed to certain sites on Hoxxes. It is only found in the Escort Duty mission type.

The Dozer is predominantly yellow in color and features two engines mounted on its side and a gigantic rotary drill on the front, as well as a robot head on the top, between the drill and the main body. It has two externally mounted fuel tanks which can be extracted and used to siphon fuel from the environment. It crawls along the ground using heavy treads but is also equipped with a rocket thruster for temporary aerial mobility. It can vocalize via high-pitched robotic warbling.

Unlike other similar mission-critical objects, the Drilldozer does not have a mobile depository on board - the M.U.L.E. is also present in Escort Duty, serving its usual purpose of storing any collected minerals gathered by the Dwarves.

Gameplay
Once the Dwarves and the M.U.L.E. have exited the Drop Pod, the Drilldozer will be delivered to the dig site separately via a Heavy Cargo Drop a few moments later - Mission Control will announce its arrival. It must be activated before it will start moving.

The Drilldozer's purpose is to lead a path to, and eventually extract, an Ommoran Heartstone. The Dozer is not outfitted with any kind of defensive utility, leaving it up to the Dwarves to keep it safe using their weapons. Since creating a path to the Heartstone manually is wholly unfeasible, protecting the Dozer is a necessity.

The Dozer's mining speed is influenced by the amount of creatures surrounding it, and it will slow until stationary if it is swarmed. For this reason (on top of Doretta's natural vulnerability) it is imperative for the team to remain by Doretta's side at all times, maintaining a watchful vigil over it while it creates the path to the Heartstone. Once the Drilldozer has finished mining the Ommoran Heartstone, it will back up and its head will violently explode off the chassis.

Doretta
Doretta has a total of 520 health split into three sections corresponding to the left engine, the right engine and the core. Each engine has ~health while the core has ~health. No matter where it is hit the left engine will always take damage first, followed by the right one, and eventually the core. It can be repaired if it takes damage by pressing the [USE] ("E" by default) key over the damaged side. The Dwarves will repair the Dozer for approximately 10-15% of its HP for every second spent repairing, reduced if under attack. It takes 10% friendly fire damage no matter the difficulty. Broken engine sections cannot be repaired in any way. It has a 50% Explosion resistance, 50% Radiation resistance and 25% Poison resistance. Doretta will move at 2m/s while drilling, 2.5m/s if only dwarfs are present, but only at 1.5m/s while being attacked. If a section’s health is fully depleted it is destroyed and the drilldozer is permanently damaged. Any damage exceeding a section health will not carry over to the next section. Mission Control will chastise the Dwarves if the Dozer ever sustains permanent damage, alongside UI elements indicating the Dozer is in danger. If Doretta is destroyed at any point before the Heartstone is extracted, the mission is considered a failure.

Refueling
At least once per mission, the Dozer will run out of fuel. Two red fuel tanks will pop out of the back of the machine when this happens, and the Dwarves must use them to extract fuel from nearby Oil Shale clusters.

Oil Shale spawns on walls in large cuboid chunks somewhat similar in shape and distribution to Bismor. It has an abnormally high resistance to mining and explosives, and is the only mineral type in the entire game to require four strikes of the Pickaxe to be turned into a loose resource chunk. Unlike other materials it is not required to be broken with the Pickaxe nor can it be added to a Dwarf's inventory or deposited to the M.U.L.E. - rather the Dwarves can simply use the fuel tanks' laser siphon to refuel Doretta. Once a tank is fully loaded, it can be re-inserted back into the Dozer. Once both tanks are fueled, the Dwarves can restart the Dozer and it will continue on its path.

The Dozer's fuel consumption rate is not influenced by its movement speed or mining - it is set to run out after digging a couple of tunnels, whereupon it will usually stop in the center of a large room. Some missions will require two fuel stops on the journey to the Heartstone. While these stops are necessary to fill up the Dozer, they are also good opportunities for the Dwarves to gather valuable resources such as Gold and Nitra.

Heartstone
The Drilldozer will conclude its journey at the site of the Ommoran Heartstone. When activated, the Dozer will start using its drill to bash the outer shell repeatedly, breaking through multiple layers of the shell until the Heartstone itself is exposed. The Heartstone site will react violently to being disturbed, and will take multiple measures to try and destroy the Dozer (and by extension, the Dwarves).

Phase One: Guaranteed swarm trigger.

Phase Two: Summons floating rocks to slam into Doretta - these deal extreme damage but can be destroyed before they hit the Dozer.

Phase Three: No longer throws rocks but causes another guaranteed swarm trigger, with increased enemy presence

Phase Four: Starts spawning Ommoran Beamers, large crystal towers which fire laser beams at the Dozer, dealing constant damage. On top of this, a slow trickle of enemies constantly spawns.

At the conclusion of Phase 4, a large shockwave will burst out of the Heartstone, killing all nearby enemies instantly. The Heartstone can then be extracted and strapped onto the back of the M.U.L.E., where the Extraction process can begin. The Drilldozer is left behind at the Extraction process, and it is not necessary to guard it while escaping.

Trivia

 * Doretta (and by extension Escort Duty as a gamemode) was introduced in Update 32: Roughnecks at Work.
 * The Dwarves all speak very highly of Doretta, admiring her creation and wondering if they could purchase a Drilldozer of their very own.
 * It is possible to pet Doretta by pressing the [USE] key on its "head" found mounted behind the drill.
 * Doretta's "head" closely resembles Bosco in many respects, such as the singular yellow eye mounted on the front.
 * It is possible to stand on Dorettas' drill while she is moving if you walk in the opposite direction to its rotation (like a treadmill).
 * If the back of one of Doretta's treads is over an oil shale when she stops to refuel, the back end of the tread will be lifted when the oil shale underneath is either being mined or extracted with the fuel canisters.
 * Doretta's head can be picked up like an ore chunk, and if carried into the drop pod it can be placed into a spot near the door. Be advised that this will not grant experience or other bonuses upon completing the mission; however, the dwarves will vocally approve.

Perforadozer