Cards work similar to armor and ornaments. They add white and blue stats they carry.In PWI you can devour lower card by higher one to increase XP of higher card. Same as inthose Card Battle games on iPad and Android. I was told that here each card is already maxed,no need to use Devour to increase its XP. That thing was done for balance.Cards cannot be leveled here as that would be WAY too OP for your stats (and for PVP too.) In order to work, each card has to be in corresponding slot.For example, Destroyer card works only in Destroyer slot, Battle card only in Battle slot and so on...You can put cards to "wrong" slots, but they add nothing while there.This is correct.Cards have levels: C, B, A, S, S+. Cards level C are the lowest, Cards level S+ are the highest.As far as I can see best are level S, because S+ were added just to allow getting highest titles forcollecting numbers of cards, but from S+ their white stats were removed.S+'s white stats were OP (maybe Extremely but that's up to you to decide) which is why they (being the stats) were removed. S+ is not end tier; S cards are. (Except for MAYBE one slot.)White stats on cards are same for "same slot card" of same level. Blue stats vary. Anyway, it isbetter to have A card of "bad" blue stats with better white stats, than B card of "good" blue statson lower white stats. Of course the best is to have higher card with "good" blue stats. For example, you can add card with Str to Wizard, and move your own Str points to Mag.But if you replace card later, you will have to reset points again. I'm too lazy to do it, so Iuse Mag card on mage class, Dex card on LA class... Unless put Atk Level, Def Level, Crit, ...^Slots also get some points when you use Nuema. You can get nuemas from nuema boxes, or frombosses in low level caves: FB29 (Qingzi), FB39 (Hercule Trioc), FB51 (Wyvern), FB59 (...),FB69 (Cenequus Polearm), FB79 (Linus the Woeful). Maybe others there too, I don't know, sorry. You can also get Nuemas from all three FB19s as well if I recall or from the boutique.Some cards require Leadership 1, some require 2, some require 3. Your leadership is shown at thevery top of the War Avatar window. Starts with 10 and you can add 8 more, 1 by 1, in Primal Worldat War Avatar Master. From God's Giving buy War Avatar Catalyst, then at War Avatar Master takequests as they appear: for 10 Catalyst, for 20, 30, ..., 80. You will need 360 Catalyst in total, theyall together cost about 18-19 million coins. (It was 37 mill 2-3 weeks ago, but Agatio helped.)All the beast and good luck in getting good cards. Browse Crimson Officer Ling in Cromagnon Villageto see what packs he can offer. You have S packs for 4 Flowsilver Coin each. Unlike other S pack thisone gives S cards only. Other one gives much more B, few A and scarce S.~~~~~I hope this description was short enough.
Added some stuff in red.
Can you explain how does one become superior to himself? You said S+ cards are OP, but that is completely wrong - if every class can have S+ cards then how does one gain advantage over another while having the same cards as his enemy?