The King is the only required piece in an army. It can move one tile in the four cardinal directions, as well as the four diagonal directions.
A King unit cannot be obtained from boxes, nor can it be upgraded.
In-game tip: Sometimes sacrificing King can still lead to victory
Difference with classic chess Edit
Unlike normal chess, the king can be captured. If done so, the king-less player will lose 25 Morale, as well as 3 Morale per subsequent turn. (Note: the morale decay doesn't start until a full turn has passed without a King, not the turn immediately following your King being captured.) It may be important to note that King can be sacrificed without an immediate loss, and therefore King sacrificial strategies are definitely possible to draw out a powerful champion such as a Queen.
Also, unlike classic chess, you can put the king anywhere, as long as it's on the bottom row. Its castling ability is also different from the classic chess.
Effect & Status Edit
If you capture an enemy champion using Minotaur, it will switch positions with the enemy King.
The Valkyrie can teleport the ally King to an adjacent location.
Vampire gives the king morale value if you have a king, and Pride's death gives half its morale value to your king as well.
The King can "swap places with an ally Champion and then move the King and champion together", which is an in-game confusing way to say that the champion move two squares toward the King and the King goes one square past the champion (The King moves 2 or 3 squares toward the champion, so that if the king started at the right of the champion, he ends up next to the champion and at its left). This move, called Castling move (or castle), can be done with any champion at distance 3 or 4 in any orthogonal direction, including vertical ones, and only once per King.
Contrary to real chess, a king and a champion which have moved may still castle. Also, the champions always move two squares (while in real chess, this privilege belongs to the King). This is definitely not a hidden information.
Castling can't be done if there are normal pieces between the King and the champion, but castle can be done through a transparent piece such as Ghast, as long as it does not occupy the location the King or the champion it castles with is supposed to end (id est, long castle is still possible if there is a transparent piece next to the king).
Note : a Prince transforming into a King has castling ability.
Note : it used to be a Fragile ability, meaning it was related in a hidden, illogical and unintuitive way to the threat system.