I'm sure it has probably been suggested before, or maybe even implemented on kRO, but I've always been a fan of the card combos since my early years in RO (been a player since release) when they mattered a lot, but they very quickly became irrelevant, unused, and forgotten. I feel like it would add some more customization back into the game if it were a thing again. Not only having to rely on a single piece of headgear for insane damage boosts.
Example:
Set bonus with Freezer Card, Heater Card, Archdam Card:
- Str +1
- Int +1
- Def +2
- SP Recovery Rate +10%
- Reduces the variable cast time of skills by 10%.
- Increases the damage inflicted with [Martyr's Reckoning] and [Rapid Smiting] by 10%.
- If used by a Crusader job type, changes the user to [Holy] element.
Something simple like increasing the stats gained to +10 and damage increased by 100% instead of 10% would add much more meaning to it and the chance to create new and unique build paths.
