Adrenaline Meter

The Adrenaline Meter is a mechanic added in Revengeance Mode, along with the Rage Meter. In order to fill up the bar, the player must not get hit for a certain amount of time while fighting a boss. Once the meter has filled up completely, the Adrenaline Mode buff can be activated by pressing the key. The Adrenaline Meter has a minimum value of 0 and a maximum value of 10,000.

The meter will build every second at a rate of 333.34 per second and takes 30 seconds in total to charge.

If the player is hit while the Adrenaline Bar is full, the damage of that hit is halved and the bar will reset and need to be charged again. This is separate from normal DR and therefore ignores Calamity's DR scaling system.

When the Adrenaline Mode buff is activated, the player receives a damage boost of +200%. This total damage boost is multiplicative and applied after other damage boosts such as those from Potions or Accessories.

The player can increase the damage of the Adrenaline Mode as well as increase the damage reduction when hit while the meter is full by using these permanent power-up items:
 * (dropped by The Slime God), which increases Adrenaline Mode damage by +15% and increases damage reduction by +5%.
 * (dropped by Astrum Aureus), which increases Adrenaline Mode damage by +15% and increases damage reduction by +5%.
 * (dropped by Polterghast), which increases Adrenaline Mode damage by +15% and increases damage reduction by +5%.

Using all three upgrades will cause Adrenaline Mode to increase the player's damage by +245% and cause any damage taken while the meter is full to only deal 35% of its damage.

With Rage
When both the Adrenaline Mode and Rage Mode buffs are active at the same time, the player receives a damage boost of +280%. If the player has the Heart of Darkness or Draedon's Heart equipped, the damage boost goes up to +310%.

Using them together ignores all consumable upgrades.

Trivia

 * Adrenaline and Rage are a reference to Ripper Mode from Metal Gear Rising: Revengeance. Because of this, Adrenaline and Rage are often collectively referred to as "Rippers" by the community.
 * Adrenaline previously had a decay mechanic, where the overall damage boost granted would be less depending on how long Adrenaline was held for while fully charged.
 * Adrenaline and Rage used to have boosted damage increases while in Death Mode.
 * Adrenaline and Rage are replacements for a previous mechanic called Stress.