Merge

Skill Level Up Merge
When improving a skill you need two of the exact same hero card (which can improve any skill on the base card, regardless of whether the materiel card has the skill or not), or a card with the skill you want to improve at the exact same level.

Up to 5 additional cards can be used to increase the odds of success. The improvement is based on both the rarity of the added materiel card and the level of the skill being leveled.

Additional Materiel Card
All tests were done with 0 level add on cards. Your chance for success improves with cards that have levels. For example, the level 6 skill with a UR card addon is 45.36, but if the UR add on card is level 242 the chance to merge increases to 57.25.

Learn Skill Merge
The order of skills are based on the ATK, DEF, INT points distributed to the base card.

The Hidden skill will only appear when the Base Card already has one of the 3 initial skills. The skills will move up filling the gap, thus unlocking the hidden 4th skill.