A battle occurs when a unit(s) is/are attacking and is/are blocked by an opposing caster/unit.
Attacking counts as an Action action. By Checking one (or more) of your units, it deals damage to your opponent's Battle Area (that means, the target is the area). In addition, the attacking player is called "attacker", while the player attacked is called "defender".
To make an attack, the attacker Checks any number of units in Normal state (the units may be a combination of both Battle Area). Those units, until the process of attacking is completed, are treated as "attacking unit(s)".
The attacker then declares whether they want to attack the defender's left or right Battle Area. At this point, the player cannot select a Battle Area which has no Hit Points AND units.
When attacked, the defender MUST declare blocking. 'Block' is a term that indicates the target of an attack. Blocking can be done by one unit or one caster (it does not matter if that card is in Normal state or Check state). If there are no units in the attacked Battle Area, the defender has no choice but to block with the caster. If the caster has no HP left, the defender has no choice but to block with units.
After the attacking units and the blocking unit are determined, both players may process Reactions (if any is played).
Applying defender-attacker attack damage:
- After Reactions resolve, and after the sum of Battle Power of all attacking unit is established, then the attack damage occurs.
- Blocking caster or unit declared by defender receives attack damage. After the damage is applied, "attack bonus" occurs.
Attack bonus is caused by an event where the last unit on a Battle Area owned by the defender is dealt attack damage and leave the area. If that happens, break one HP of the caster on that Battle Area. If the caster has 0 HP, the attack bonus does not occur.