this entire post is going to be one big IIRC
Offensive (red) meter builds when you attack. Defensive (blue) meter builds when you block.
Red meter is used for Supers, Unblockable attacks, Roman Cancels.
Blue is used for for more defensive oriented supers, instant blocking, and air recovery.
When both are full you can use your Critical Art.
Boost Drive costs 1 red and 1 blue, and is something like that Vampire Savior's Dark Force.