What is the reasons to kill the mid boss?

[Disco Battle]

what does it do??

[LeoTheGrey]

It drops a buff that makes all your candle dudes temporarily stronger and makes the time for each team member's next respawn halfed. Just be aware that you don't get the buff from the boss, but from charge punching the crystal that spawns after killing the boss. Meaning an enemy player can steal the buff if your team doesn't grab it fast enough.