
Originally Posted by
Ramazan
Q: Why do some buffs stack and not others?
A: Each buff and debuff in this game has a hidden type attached to them.
For simplicity sake, we will call each hidden type Type A/B/C/Stacking/Summon.
Type: A/B and Summon are very commonly used.
Type: C, namely Sol's and Zephyrus' attack debuff and Cthulu's def debuff.
Type: Stacking, currently only the R rarity KH Caspiel possess such type of debuff.
(Zephyrus, Cthulu and Caspiel are not available at launch.)
Simply put, Different type of buffs and debuffs WILL STACK while same type of buffs and debuffs WILL NOT STACK.
For more information about which type each buffs and debuffs belongs to, refer to the JP wiki and google translate the page. (Unless someone wants to help me with this due to skill names still being unknown in the EN version.)
JP wiki page about buff and debuff type: