Don't worry, it's optional.
Basically, it's an ordinary game of lockdown.
The main feature?
You can only use the standardized items of your tier. Two weapons and no trinkets. So on T1 it's the proto gear. On T2 it's solid cobalt gear. On T3 it's the... Yeah, you probably guessed.
Oh yeah, costume gear is allowed because everyone has the same armour anyway.
The point of this is that it's predictable and balanced, so newer players may enjoy it more. Heck, some just prefer a predictable fair fight. Some like the unpredictablility of regular lockdown. It's your choice, really.
Inspired by the Proto League.
"You can only use the standardized items of your tier. Two weapons and no trinkets. So on T1 it's the proto gear. On T2 it's solid cobalt gear. On T3 it's the... Yeah, you probably guessed."
Royal Jelly Set, amirite?