Atonement is a gear perk that speeds up how fast your Supremo recharges, at the cost of making you noisier when you move. It suits players who fire their Supremo as often as possible.
Your Supremo backpack refills faster, so you can use Armagedón Strike, Fuego Loco or Venom Salvo more often in a fight.
Wear one of the gear pieces that carry it: Prophet's Boots. Each piece only takes one body slot, so plan around the other perks you want.
Yes for loud, Supremo-heavy play. Stealth players should skip it.