The Boom Bus was a limited time promotional unit originally released on the weekend of May 3rd, 2013. Due to popular demand, Z2Live brought back the ability to produce this unit on the weekend of July 19th, 2013. Surprisingly, this limited time unit does not cost and can be produced in the Vehicle Factory using resources.
The Boom Bus has a variety of area-of-effect, crushing-type damage attacks. Sonic Boom affects a large portion of the battlefield with moderate damage and a chance to stun.
The Ultrasonic Shriek is gives the Boom Bus a more damaging attack with increased critical bonuses against Metal units, making it somewhat of an anti-armor option. As a result, this attack has a uniquely-shaped, more focused area-of-effect. It also has reduced ammo and a lengthier reload time compared to its other weapons, limiting its role.
The Boom Bus can also research and unlock an attack called, Brown Noise. This attack affects the entire field with low damage and a chance to inflict a lengthy stun status effect. The damage and chance to stun are determined from the Boom Bus' position on the battlefield, so the farther the enemy are from the Boom Bus, the lower the damage and chance for stunning the enemy will suffer. So a Boom Bus using its Brown Noise attack from the 2nd or 3rd row will be less effective, while the enemy unit 1 space away (i.e., directly in front of the Boom Bus) will suffer the full brunt of the attack. The damage is negligible, so Brown Noise is best used as an attempt to stun multiple enemies, potentially taking out an enemy for two whole rounds. Unfortunately, Vehicles are unaffected by this.
Before the 3.1 Patch, multiple Boom Buses could lock down an entire army with the Brown Noise attack, which was able to stun the entire battlefield, 100%. This made Raider and critter encounters trivial as they would never have a chance to attack. In PvP, the unfortunate player to face this army while fielding mostly infantry would find themselves passing each turn and just watch their army be picked off. If it wasn't Brown Noise, the Boom Bus' Ultrasonic Shriek also inflicted Stun, and to vehicles, like tanks.
Z2Live never intended for "stun-locking" to be a gaming feature, especially when it made encounters too easy or PvP "unfun" for one side, so they made major changes to the Boom Bus with the 3.1 Patch, with the intent of splitting the roles of the attacks, i.e., Brown Noise has a chance to stun the army, Ultrasonic Shriek does damage and Sonic Boom sits in between. They subsequently released the Signal Jamming Drone and the Legendary Mammoth, capable of "stun-locking" opponents.
Sonic Boom base stun chance reduced to 50% from 200%. (The base chance is reduced in splash areas, so there was a large chance of stunning multiple targets.)
Ultrasonic Shriek: ammo decreased to 2 from 3, reload increased to 8 from 3, stun status effect removed.
Brown Noise base damage reduced to 18-42 from 36-84, stun chance reduced to 80% from 200%.
Plague
320
75%
100%
100%
60
and can be produced in the Vehicle Factory using resources.
Stun, and to vehicles, like tanks.
3
SP
Total
Bravery
Defense
Dodge
Ability Slot
4h
6,528
3,975
5
3
1,400
Oil
Nanopods to train, the second being the Unicorn Trooper.
