"Debuffs" are an event mechanic that consists of weakening the final Boss of a given map. Debuffs are some form of damage bonuses against the Boss and sometimes its fleet, and are unlocked after completing several gimmicks, depending on the map and the difficulty.

Overview

When a debuff phase is available on a map, it can only be unlocked after reaching the Last Dance of the Final Boss of the said map.

To unlock a debuff, the player must complete several gimmicks that vary across maps and difficulties.
Once the debuff is unlocked, the effectiveness of the debuff is visually indicated by the "Final Boss CG" being changed from its "Last Dance" form to its "Debuffed" form.
- Once the map is cleared, the debuff effects are always applied, even if it was not done for the last dance clear.

The bonus provided by a debuff is varied:

It is always a damage bonus, being either:
- A reduction to the enemy's armor ,
- A post-cap damage modifier for the attacking fleet (probably cases of misinterpretation of armor reductions).
It also often provides an accuracy and evasion buff for certain ships or ship types.

The bonus most often applies to the Boss Node only, but can also be effective across the whole map depending on the event.

In all cases, the main boss flagship will receive the most important debuff, with some of its escort often being debuffed too.
The bonus can be heterogeneous, depending on the ship or ship type, often following the other historical bonuses.

Doing the debuff never is mandatory to clear the map.

In almost every case, doing the debuff is highly encouraged, at least in harder difficulties.
Clearing a map usually applies the debuff effects automatically, even if it was not applied for LD, making further farming easier.

Given how many variations there are in debuffs, please refer to the latest events page for information.