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 three. 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.