BGM:  - Demise by Ethan Meixsell
The Spark has a black body with two tiny thunderbolt-shaped spikes on the front of its body. There are two larger normal spikes extending from the sides of the body, with the Knight symbol on it. On the rear a Stalker-type Barrel extends from it upon a stout trapezoidal base.
Towards the corners (but not at them) there are four light gray circles. If any of the Spark's attacks happen to hit them, whether electric arc or bullet or projectile, the entire room gets a shock and the Spark restores 500 health while every tank gets hit for damage equal to 1/5 of their max health and Dazed for 3 seconds. Any Shocker branch tank is not affected, though. Cooldown of 80 seconds after this has happened.
Leptonborn: Passive ability. When killing a tank, gains a movement speed boost for the next 30 seconds. It's small, but this effect stacks and has a limit of +20 movement speed boost, and the duration stacks as well.
Why They Call Me The Spark: Used as his first attack. Launches a high-speed YELLOW bullet forward that crackles with electricity. It deals heavy damage to anything it hits. Oh, did I mention it has a splash radius too? However, it takes 2 seconds to charge and the Spark's spikes flash yellow during that time.
Thunderbolt Transformation: Reverses himself and fires an electric bolt from the Stalker-like barrel. This bolt is similar to that used by the Chain Mage, but jumps onto up to 20 targets. It will prioritize the circles in the corners over tanks if the jumping bolt is close to them. If a tank is hit, they get Paralyzed for 5 seconds.
Going for the Gold: The 5 tanks closest to him are magnetized together, charged with electricity and turn gold. The Spark moves up to the tank ball and smacks it with one of his side lances, sending it bouncing across the room. Tanks hit get Confused for 7 seconds and medium damage.
Acid Rain: The Spark unleashes a hailstorm of yellow Gunner bullets which don't have any secondary effect when they hit tanks. This is the only attack which CANNOT activate the light gray circles near the corners of the room.
Solar Vortex: Ultimate, used only once at any point during the fight. All tanks get Burning and Blinded for 5 seconds, while being damaged over time. Very dangerous, kills 80% of the tanks outright. Good thing you spawn at level 45...