Details about SUB-ZERO

Sub-zero is a Black Market Goal Explosion.
Goal Explosions are shown when the player shoots a goal. Black market goal explosions are very rare and awesome to watch. You can equip them inside the customization window in the goal explosion tab.
To get the Sub-zero Goal Explosion you can either open a specific crate with a key or trade with other players.
You can search for trade offers with Sub-zero here.

Sub-zero Black Market Goal Explosion