'Weaken' is a debuff that causes the next hit taken by the affected target to be a guaranteed Critical Hit. 'Weaken' can be seen as a debuff counterpart to 'Critical Boost'.

'Weaken' effect will be consumed once the target has been damaged by any attack that is able to perform Critical Hits (normal attack, damaging skill, and delayed damage), or wear off on its own after 3 turns. However, some costumes maintain 'Weaken' effect for 1 turn, guaranteeing Critical Hits towards affected target until the end of the turn. 'Weaken' is not affected by bosses' Status Effect Immunity, which makes lasting 'Weaken' effect an efficient anti-boss tool, especially in Mythic Raid.

Empress Sun Shangxiang and Jeong-yeon are the only heroes to date to have lasting 'Weaken' effect without costume and the only heroes to have lasting 'Weaken' effect affecting more than one target.

For the full list of heroes with 'Weaken' effect, see below: