Tips and Strategies
Keep track of your daily missions.
These missions earn you crystals, which is the game's premium currency, which you can then use to summon high-ranking monsters. Most of these missions can be completed as you play along, for example the mission where you only have to spend 20 energy, and in return it gives you 3 crystals as a reward. Complete all of the daily missions and you will also be rewarded with crystals. However, you may also want to focus on the regular missions and Achievements that rewards you with more crystals, so you can stack up as you will need them as you advance to tougher stages.
Follow the story.
Aside from the daily missions, regular missions can be very rewarding plus it requires no deadlines to be met. The Achievements start out easy on the first phases of the game, but as you complete them it will increase in difficulty. Completing these missions will most likely reward you with a lot of crystals, which you can then use to purchase a variety of useful items and summon top-tier monsters.
Add as many friends as you can. This will allow you to earn Social Points which can also be spent to summon monsters. Although the monsters summoned via SPs are usually weaker, they can still be used as additional experience points for your team. Also, remember to only add active friends otherwise you won't gain any SPs. Delete your inactive friends and make room for the active ones.
Annoy your rivals.
Rival battles always reward you with crystals, so when the opportunity comes, fight them as much as you can. You may have to wait for a short period of time to battle them again but it's surely worth the wait!
Equip your runes.
Runes, especially when upgraded, can give your monsters stat boosts that can give you the winning hand in battles. Make sure to upgrade and equip them before going off to do missions. Equipping a certain number for each rune type also triggers a set effect which is an additional boost. For example, equipping 2 Energy runes will increase your monster's HP by 15%, so it would be useful to units with a low base HP stat or to further increase the base HP of defense-type monsters that you can tank to defend your offense-type units.
That's just an exaggeration, but you get the idea. Summon as many monsters as you can to level up the best monsters in your team. The more monsters you get as disposables, the more experience your main monsters will have. This is an effective strategy aside from grinding to make your monsters stronger if you have no time to kill.
Invest on your defenses.
While focusing on levelling up your arena fighters is a very important factor to progress in the game, you may also want to invest on adding Arcane towers. Each tower deals 300 damage to the opponent's team, and you can place 10 of them which totals up to a massive 3000 damage. With this and a good defense team, it will be less likely for you to lose.
Aim for the top!
Always battle in the arena so you can increase your weekly rank. The higher your rank is, the better your rewards will be at the end of the week. Ranking is decided by the victory points you earn from winning, so make sure you stack up on Arena invitations!
The amount of victory points rewarded after an arena match is based on how strong your opponents are. The stronger they are, the more victory points you earn, so try to defeat opponents with at least a few hundred more victory points than yours. However, don't be too risky, as losing a match reduces your victory points as well. It's better to avoid making mistakes and battle weaker opponents with you having a 100% chance of winning, than losing both a match and victory points from fighting an opponent far stronger than you.