Like I had explained in the Dark Summoner review, these social, pseudo-card games are not quite complicated in its gameplay like most Trading Card Games. It mostly boils down to having the bigger numbers, but at the same time, has a little more depth in Deity Wars than Dark Summoner does.
Gameplay - Deity Wars has PVP elements as well, though the game has a much more Co-op feel than PVP compared to Dark Summoner.
Unlike Dark Summoner, there are no great guilds/factions to join. In fact, you are automatically placed in your own guild as everyone seems to start off with a guild. There are definitely benefits in joining other people's existing guild rather than staying in your own however, unless you absolutely want to start a new guild yourself. These guilds are closer to Dark Summoner's Clans where you level up the clan/guild to gain more benefits for all of the members, as well as clan/guild members acting similarly to allies.
Similarly to Dark Summoner, you have Action Points (or energy) and Battle Points. Action Points are used for missions, and Battle Points are used for PVP and Raid Bosses. However, what differs here is that you don't have freedom of how much AP and BP you have as your max AP is determined by your level, and your max BP is always at 100. Also note that attacking other players via PVP costs 50 BP, and attacking a Raid Boss costs 20 BP each (except for the first attack against a Raid Boss discovered by your ally or guild mates, which has no BP cost).
You still want to make as many allies to both increase your stats as well as for Raid Battles as well, but both play out differently than in Dark Summoner. In Deity Wars, leveling up and adding allies will give you MP which you can set to either Attack MP or Defense MP. Attack MP is used for summoning your cards for attacking Raid Bosses and other players, and Defense MP is used for summoning your cards when defending against attacks from other players. Stronger/rarer cards generally cost more MP to summon, so you will want to get more MP to be able to summon more, stronger cards to be effective. Also, you can summon up to 10 cards when attacking and defending. However, managing the cards can be automatic, as the game can give you the best card combination for maximizing your Attack or Defense stat with what MP you have available.
The missions interface you do in Deity Wars is more polished and graphically appealing than Dark Summoner's. Not to mention how it is more eventful and less RNG swingy with the rewards. A reward is guaranteed if you spend 3 turns in the mission, with enough AP left for another turn, without interruption from the mission completion screen or a level up screen. Also, there are other random events that occur during missions, like Raid Boss encounters and randomly recovering some AP or BP through other encounters.
Raid Bosses provide a Card Pack Ticket used for summoning a card when defeated. This goes for everyone that participates in taking down the Raid Boss, as all of your allies and guild mates can help with attacking the boss. In fact, doing so is much more efficient as you build Chain Attacks when you alternate attacks with other players within 10 minutes of each other, which increases the amount of damage you do against the boss. After each successful take down of the boss, they grow a level for the next time you encounter them, having more HP and dealing more damage against your cards as well. They are still timed for 2 hours before they escape, so working with other players is required once they grow too strong. This aspect is what makes Deity Wars much more Co-op oriented, which I find to be neat. Don't worry too much about the Raid Bosses getting too strong to the point of where you can't take them down however, since the game seems to rotate out old bosses for new, starting again at level 1. At least, that was the case with the first two Raid Bosses that I saw when I first joined Deity Wars. There is a good chance that this trend will continue to keep things fresh and eventful.
Among the mission rewards are collectible loot, which, instead of summoning a Raid Boss, grants you Materials. Materials are stat-boosting card enhancements that goes inside slots in cards. Each playable card can have between 1 to 5 slots, making cards that have 5 slots superior as you can put more materials in them to boost their stats higher. You can also gain materials from maxing out a card's level. Each card has a max level that they can reach, dependent on the card's rarity. If you unlock all 4 materials for each of the card's evolution stages, then you also unlock an additional material for completion as well. My recommendation is to aim for the completion bonus with higher ranked cards since the materials you get will most likely better than the lower ranked cards, although they may be easier to max as their max levels are lower. The higher ranked cards with increased levels will most likely be a good addition to your deck until you get another of the same card to evolve them with.
In Deity Wars, all playable cards can evolve, and usually have 4 stages. Each of these 4 stages have their own material reward for maxing the levels, and each time you evolve, the card's level returns back to 1. However, if collecting materials isn't a priority, consider evolving the card to its final stage immediately, and level it up to achieve higher stats early on. An important note though is that the number of slots (and their contents) will always remain the same as the main card you are evolving, while disregarding what slots (and their contents) the card you're using to evolve has. So don't waste your materials on a card with few materials, and use cards with the higher number of slots as the base card to evolve, even if that is in a lower evolution stage. It will still upgrade to the next stage of whichever is the highest evolution stage.
Another important thing to note about Deity Wars is that evolving and leveling up cards cost Gil, which isn't as plentiful as gold is in Dark Summoner. You will find yourself running short on gold if you're not efficient with your leveling, or simply fusing lots of cards. When leveling, try to maximize how many cards you can use for enhancement to reduce your overall costs. Kujatas are uncommon cards, but they provide a lot more EXP than normal cards for enhancements. Use them wisely to reduce costs as much as possible. Leveling up costs more as the card's level is higher, so if you can max its level from level 1, it would be the cheapest, but will also require many potent EXP enhancing cards like Large Kujatas or better.
Graphics - Much more colorful than Dark Summoner, and to me, much more appealing, but perhaps it's because of the anime-like style artwork. I do definitely enjoy the artworks in Deity Wars in general though; a lot of the cards appeal to me. It's also interesting to see each card change slightly in each of its evolution stages.
Sounds - There are many music tracks in Deity Wars, and they certainly provide some very fitting moods for each screen you're on (except for the menu screen, which is oddly silent). There are options for adjusting the music and sound volumes, so you can adjust it to whatever is most comfortable for you.
Overall - Deity Wars is certainly a more eventful game, and feels more involved with the co-op aspects of the game. I find myself checking the game often to see if any of my allies have a Raid going that I can assist. Deity Wars also has a story that is more involved as you do missions, unlike Dark Summoner which forgoes story for the concept of getting stronger with the dark theme they were going for.
Finally, here is my referral code to help you with some starter freebies. Unfortunately for me, I missed out on entering a referral code when I signed up (The screen went away before I got to enter a code), so I missed out on the freebies myself. Hopefully that won't happen to you guys. You get a Legendary CP ticket, granting you at least a R rank card when used, and some extra potions to start you off with when you use a referral code. The referrer will also get a special card for each referral made that are only obtainable through referrals. They are special in that they have 20 evolution stages.
Referral Code: WUJ9666
Edit: I've been getting some questions regarding Deity Wars, so I figured I'll just answer some here.
Q: Any tips for leveling and evolving cards?
A: It might be best to forgo leveling any non-fully evolved N and NN ranked cards. You can collect some easy materials for reaching the max level of 20 or 30 from N and NN ranks, but the materials you get aren't worth the gil and cards for fusing. On the other hand, if you want to get the achievement bonus for maxing out card levels, N cards will be the ideal cards to do it with, but it will probably not help you maximize your Attack and Defense stat potentials.
Also, save your Kujatas for leveling R rank and above cards, since they need them the most. I am also looking for a chart that shows what combination of Kujatas can maximize cards' levels in one shot for a reference guide. I will post a link if I find it.
Edit: I have done some analysis on leveling with Kujata and the results can be found here.
Q: What are some good deck building strategies?
A: You will generally have two separate decks. One for attacking, and one for defending. When defending, I believe if your total Defense stat is higher than your attacker's total Attack stat, then you win. So I would suggest sorting your cards via DEF Descending, pick out some of your best defensive cards you want to dedicate for defending, evolve them, level them, and give them some good Defense materials. If that card has a skill for raising your party's defense as well, even better.
As far as attacking goes, it depends on whether if you want to focus on attacking Raid Bosses, or other players. If you want to attack other players, the same strategy above, except with ATK Descending sort and boosting attack as high as you can will do you justice. But when it comes to Raid Bosses, if your cards die from a single hit from the boss, you won't be able to maximize the damage you do against them. So for Raid Decks, you will want cards that have both good Attack and Defense stats to deal the most damage.
Edit: Instead of raising cards evenly for raids, simply look for cards that specialize in dealing more damage against raid bosses. Also, at really high raid boss levels, they will manage to defeat your cards in one hit, so focus on raising attack on them instead. You will always attack first, so you want to hit as hard as you can.
Also, look for cards with skills that helps with your deck. Often times, your cards will raise the stat of a certain element of Heaven, Hell, or Earth. Try to build a deck consisting of all of the same element that also focuses on either Attack or Defense. Your Attack and Defense decks can be a different element as separate decks do not interact with each other.
Q: What should I do with my materials?
A: My suggestion is to save your strong materials, like +2000 and above, for a really good card. A really good card IMO would be a base RR or above with 5 slots for maximum growth potential, and make note of how you plan on using the card as well. If the card's Attack is higher, then focus on raising its Attack even higher, or Defense if Defense is higher.
The lower end materials, you could either stuff them on your N, NN, and maybe R cards, or consider trading them off for a life/battle potion or two. I would just raise a N and NN rank card with 5 slots with some of the weaker materials since it's nice to have a decent card for a low MP cost to fill in some spots for cheap.
Edit: When evolving your cards, I have learned that the Evolve card (first card chosen to evolve) gains 5% of the Evolver card's (second card chosen to evolve the first card) stats. What this means is that you want to raise the stats of the Evolver card to make your final card have more stats than normal. Leveling up the Evolver card instead of the Evolve card is a given, but you could also insert your unneeded materials in the Evolver card's slots as well to help transfer more stats to the evolved card. Note: That means you want to level up the card with the lowest number of slots first, and leave the highest slotted card for your last Evolve card so that you can put your best materials on it to have the highest statted card possible.
Q: Any tips on how to get better cards?
A: I've heard that if you summon cards in a bundle of ten, you'll have a higher chance of finding rarer cards, but I'm not entirely sure if this is confirmed or not. However, considering how quickly you can accumulate Raid Boss CP with enough allies, might as well save up until you have ten anyway.
Aside from that, you can try taking a look at what's in the Market. People may be trading off some cards that you might want for Life or Battle Elixirs. So if you have some Elixirs sitting around, you might want to consider browsing the market for some better cards. Although, depending on your situation, you might want to use your Life Elixirs to level up faster, as having higher MP to bring out stronger cards might help you get stronger more than getting better cards. Which naturally means, Life Elixirs are worth more than Battle Elixirs... usually. An exception to this is during events like Guild Wars where many Battle Elixirs are consumed.