I've mentioned this in-game a couple of days ago, but I have come up with an idea to improve the class combos further, specially now that increasingly better gear is becoming available.
Currently, in order to get any benefits, you need all pieces equipped at once. That's 5 card slots taken for every class(6 for mage), which gives you basically no flexibility.
This proposal I'm coming up with involves changing the sets, so that they'll activate if only 3 of the cards are equipped. Any of the 3. For this example, I used the Swordsman, Knight and Crusader sets to illustrate.
>the cards that actually make up a set remain the same
>you only need 3 of them to activate set effects
>to prevent multiple activations, this means that you can ONLY have 3 of the cards equipped. If you have more than the required pieces, it will not work
>second class combos used all the same pieces as the first class combos, and so they cease to exist in isolation
>to get a second class combo, you need to have the first class combo active and then add a 4th card that activates that second set
>you can only have one of the second class combos active
Swordsman set are the Turtle Island cards(Assaulter, Heater, Freezer, Permeter and Solider). In this example, you only need to have 3 of them equipped to activate the effects(STR+10, among other things). Add in either Archdam or Tarou and it becomes ,respectively, Crusader(STR/INT+3) or Knight(STR/DEX+3, also Tarou card itself gives 2 str) sets. Trying to have all three at once defaults to Knight Set.
In every case, it results in less compromised slots and/or a choice of which slots to dedicate. I'll write up a Proposal for this change soon, but for now if you have questions or concerns, I'll try to answer them.