The magic shop is one of the most valuable buildings you can purchase. Build it beginning at level six, then go there and purchase everything that’s useful, from runes to silver star monsters to scrolls. This is one of the fastest ways to power up your team – load up on silver star monsters and max out your best team members. It’s recommended to max out your tanks and your healers first, to make it very difficult to die. Fairy, in particular, is both a tank AND a healer, so max her out first.
You can evolve a monster, but you have to level it up to the maximum first. The maximum level is higher depending on how many stars your monster is worth. Evolve your monster, and it will go right back down to level 1; however, its stats will increase still. Then when you power up your monster again, its experience levels will skyrocket just like in the beginning, causing it to gain a gigantic amount of experience points for a big stat boost.
If you’re still having trouble with a level, and don’t have any of the required silver star monsters or whatever else to power up, go back to old levels that you have already beaten and play them again and again, grinding for experience points, for monster experience, and for mana (AKA the blue crystals).
Depending on how far you can get on the level, though, it might be even more expeditious simply to get as far as you can in a hard level, beat the first two waves and lose in the last wave, and keep doing that over and over, as that can earn you more mana and more monster experience – although you won’t earn the treasure that usually comes with it, too.
If simply engraving runes is not enough to put you ahead, power up your runes. It’s recommended to take your rarest (highest star level) runes and power them up first. This requires a fairly small expenditure of mana, which grows as the rune powers up, and the chances of success will drop as the rune levels up. Level up all of your runes evenly (at least all of the equipped ones).
You can speed up battles massively by putting it into 3X the speed and automating the battle. For tough battles, though, you’ll want to target one enemy at a time, and for even tougher enemies which require more strategy, you will want to take off the automation so that you can pick all of the moves, and which enemy to target, by yourself. targeting during auto-battles has flaws of its own that require this: for example, your party members won’t use any healing spells when an enemy is auto-targeted.