Infected Vengefly King

Infected Vengefly King is the second, and much more difficult version of the Vengefly King boss fight.

Locations
Infected Vengefly King is located in Forgotten/Infected Crossroads. His arena is atop a high ledge that you can only get to with the double-jump ability. When fighting it in the Infected Trials, it is instead called the "Vengefly Usurper". This one has the Acid Spray. There is also a Vengefly Usurper nest located in the Howling Cliffs. You just need to complete the Acid Quest to do it. Scorpion will help you battle it though, since at the time it's equal to the power of the one in the Infected Trials.

Behaviors and Attacks
Similar to Furious Vengeflies, they are incredibly aggressive and hostile. Also similar to Furious Vengeflies, they'll see you faster then you'll see it, so just swipe where you hear the screeching.
 * Summon: Infected Vengefly King will summon Furious Vengeflies which will stay in the arena until you kill them.
 * Infection Scream: Infected Vengefly King will scream and will spit out anywhere up to 5 infection blobs at a time.
 * Swipe: This move remains the same from the original fight. Infected Vengefly King will swoop down at Ghost, similar to how the Vengefly King does it, but faster. Shade Dashing is recommended during this attack.
 * Infection Floor: Temporarily the floor will turn into a pool of infection and the knight will have to cling onto the wall while dodging Infected Vengefly King's other attacks. It is possible but quite difficult to get damage on him while the arena is in this state.
 * Acid Spray: Blasts acid out in a line from whichever side of the room it's in, to the other side. The only way to dodge this attack will be to Shade Dash through it, similar to the Traitor Lord's Wave Claw attack.