After the recent addition of alternative skins, many players have noticed a bug that increases Mona and Barbara's attack by 48%. To achieve this, you will need new skins to pick up in patch 2.4. Barbara's costume could be obtained in the event "Echoes of Legends", is now available in the in-game store, for 1680 Creation Crystals.
Procedure for calling a bug
- Equip Mona or Barbara in Epic of the Dragonslayers.
- Switch to the heroine in the world.
- Dress her up in an alternate costume.
- Choose any other character from the squad.
The bug was found by a user under the nickname Nineosix.
If these conditions are met, a bug will work and Mona / Barbara will receive permanent attack increase by 48%. In the characteristics of the hero, the increase in numbers will not be displayed, you can notice the changes in the very first battle. Wherein in the abyss, the bug does not work, but will work in the world, even after changing the unit.
We also draw your attention to the fact that a new web event has started on January 28 Festive Feast of the Adepts with many interesting activities and generous rewards.

So 48% comes from the passive of the Epic 5th awakening, there is no bug here, and costumes are not needed
If I understand correctly, in this case the buff works immediately on the 5th awakening (even if there is no such buff on the weapon) and without a time limit.