Purchase new weapons and equipment to improve the amount of coins you can gain. You will also need to upgrade your weapons and equipment to keep them useable over time. Farm previous levels for resources until you have enough coins to purchase what you need.
Health potions
Watch your health, especially when you are battling against a strong opponent. Match as many health combos as possible, as well as using lots of potions. Also consider having poison antidotes ready. You have to either cure your poison status or quickly complete the level before you end up dying.
Health potions can be used at any time, but are best saved. When possible, allow your character to recover without them and only use health potions during difficult fights.
Upgrade health potions as soon as possible. Although this will be expensive, it allows them to recover more of your health.
Matches
Before a battle in Campaign mode, tap the next location. A small text box will appear, revealing which jewels will be required. The box also shows neutral jewels which will not benefit either player. Take note of which gems will power-up your opponent. If your main powers are powered by the same jewels as your enemy, every time you match them you will also give your enemy an advantage and an opportunity to attack. If needed, temporarily convert your main attack in the marketplace before a battle to take advantage of the neutral gems. By doing this, each time you match those previously neutral jewels, the enemy will not gain anything.
Your opponent will sometimes mark a gem, highlighting it with a red circle with a number. Each time you make a match, the number will decrease. When it reaches zero, you will be damaged significantly. To prevent this, match the marked gem to destroy it. You can also use skills such as the Warrior's Block to increases the countdown by 3.
Match five gems to create a special gem. Their effects will vary, but the most common will be the white star which will damage an enemy over time. When the white star is active, do not make any moves; if your enemy is already at low health it may give you a victory.
Spells and abilities
Each class must equip various spells and abilities for offensive, defensive and tactical abilities to be effective.
Warrior: Use Strike as your standard attack. Green and Purple are usually the least used of all jewels. Dodge is a good way to defend. For your tactical ability, drop Power Strike when possible and upgrade to Crow Swarm
Rogue: Mutilate, Shadow Cloak and Killing Spree will work well.
Mage: Fireball does a lot of damage, but charges slowly. Use Arcane Shot to do damage more often. Frost Shield is an effective defense. Chain Lightning can affect a large portion of the level.
Various Game Tips
Tip 1: Gather specific gems to charge your specific abilities.
Tip 2: Match 4 gems to produce a special gem.
Tip 3: Your enemy's ability is in the lower right corner.
Tip 4: When the bar is completely charged, the enemy uses his ability.
Tip 5: As you can use ability when the bar is completely charged.
Tip 6: Your health will certainly renew with time however you can use potion to renew a few of your health.
Coins...