The power of your Champion and the effectiveness of their Bonuses depends on the following parameters:
Type
There are 28 Types of Champion. The type of Champion you should use depends on the action you wish to take. For example, if you're attacking a Beacon, a "Beacon Offense" Type Champion would be the logical choice.
Only Champions that boost Resource Production, Spying, and Castle Defense can be activated in the "Castle" tab of the Champion interface.
Rarity Grade (I to V)
Champions are classified according to Rarity. Each Rarity is given a Grade. The higher a Champion's Rarity Grade, the more powerful they are and the more difficult they are to find.
Rank
In general, the higher the Rank of a Champion, the more powerful their bonuses will be. However, Champions at the earlier Levels of a higher Rank are slightly weaker than those at the highest Level of the previous Rank, although they can be improved dramatically.
Level
Ranks are split into Levels. To increase your Champion's Level, you will need to earn XP. Higher Level Champions are stronger than lower Level ones, but the maximum Level a Champion can reach is limited by their Rank. For example, Rank 1 Champions can reach Level 15, while Rank 6 Champions can reach Level 30 (40 if enlightened).
Skill Level (0 to 5 per Skill)
Most Champions have a set of 4 Skills that affect one of the 4 Unit types (exceptions are the Spying Type Champion, which specifically improves Spying Units, and Resource Champions, whose Skills affect Resource Production and Barn/Warehouse capacity).
Enlightenment Level (0 to 5)
There are five stages of Enlightenment, and each one boosts all the Skills of your Champion. A Champion with the Rank of five or six can only reach their highest Level through Enlightenment.
Element
All Champions have an Element - Earth, Water, or Fire. Each Element performs better against a certain other Element. Water beats Fire, Fire beats Earth, and Earth beats Water.
If you send Champions of different Elements to a location, a "Dominant Element" will be selected to represent your forces.
For battles at your Castle, you can choose which Element you wish to be Dominant. At other locations, your Dominant Element will be the single Element represented by the most Champions.
If you do not have a Dominant Element, you will not be able to receive the Elemental Bonus to Champion Skills during battles. If you do not have a Dominant Element, but your opponent has Champions in a battle, and a Dominant Element is selected for their army, they will receive the Elemental Bonus regardless of which Element is Dominant, as no opposing Element will be present.
Sometimes no Dominant Element can be selected at battles outside your Castle. This will happen if no single Element is represented by the highest number of Champions (for example 1 Earth, 1 Water, and 1 Fire, or 0 Earth, 2 Water, and 2 Fire). Make sure to check which Champions you are sending to a location in order to avoid this scenario. If your Dominant Element beats the enemy's Dominant Element, you will receive a 25% bonus to your Champion's Skills.
Navigating The Champion Icon
Each of a Champion's key stats can be seen at-a-glance by viewing their Icon in your Collection. The stars in the bottom left corner of the icon indicates a Champion's current Rank. The sphere in the upper right corner represents a Champion's Element. (Gold/green is Earth, orange is Fire, and blue is Water) The number in the bottom right corner of the icon is the Champion's Enlightenment level. The top left corner will show the Champion's Level.