Panic is the most common psychological effect. When troops see their friends running away this will upset them: some will lose their nerve, a few may bolt for it, causing others to follow and soon the whole unit is fleeing away from the battle in blind panic. Some troops are steadier than others as indicated by their leadership value. Troops with a high leadership are much less likely to panic than troops with a low leadership. A unit must take a panic test in the following circumstances.
Test at the start of your turn if there is a fleeing friendly unit within 4". You do not have to take this test if your unit outnumbers the fleeing unit as the sight of a few rag-tag stragglers is insufficient to cause panic. For example, if you have a unit of 10 models and there is a fleeing unit of 15 models within 4" then you must test. However if there are only 5 fleeing models then no test is required. Note that it is the size of the fleeing unit which is important, not the number of fleeing models within 4".
Test if a friendly unit within 12" is broken as a result of being defeated in hand-to-hand combat. It is best to work out all combats and establish all broken units before making panic tests for units nearby. You must also make this test if a friendly unit is completely eradicated in hand-to-hand fighting.
Such a unit cannot be broken as it no longer exists, but the sight of its destruction amounts to the same thing. Only one panic test is required regardless of how many broken friendly units are within 12".Test if you are already fighting in combat and you are charged in the flank or rear by another enemy unit. If the enemy unit is smaller than 5 models then no test is required as there are too few to cause panic and the extra attackers are absorbed into the general carnage. Make this test as soon as chargers have declared their charge and if they are within charge range. If they are unable to reach the unit no test is required.
Test if you sustain 25% of your number as shooting casualties in the shooting phase. For example if a unit of 12 troops takes 3 casualties it must test for panic. This represents the panicking effect of massive casualties from intense missile fire. Make this test as soon as the 25% barrier is crossed. This may result in a charging unit panicking if, for example, it is attacking a unit of bowmen which stands and shoots at it.
A unit which fails a panic test will flee in the same way as a unit broken in hand-to-hand combat or a unit fleeing from a charging enemy. If a unit panics at the start of the turn because of fleeing friends within 4" it may not attempt to rally that turn, but must flee during its movement phase. If engaged in hand-to-hand combat when it panics then the normal flee and pursuit rules apply: the fleeing unit may be pursued and destroyed in the same way as a unit which breaks following defeat in combat.
For example: At the start of their turn a unit of 10 Goblins is confronted by a fleeing unit of Goblin Wolf Riders within 4". There are 12 Wolf Riders so the Goblins must take a panic test. The player rolls 2D6 and scores a 3 and a 5 which adds up to 8. As the poor old Goblins only have a leadership of 5 they fail their test. The Goblin unit panics and must flee in its movement phase. As the Goblins have a normal move rate of 4" they flee 2D6" towards the nearest table edge, moving away from enemy where possible.
For example: During the hand-to-hand combat phase a unit of Orcs is defeated and broken. All friendly units within 12" must take a panic test, which in this case includes a unit of Boar Riders and a unit of Goblins nearby. Panic tests are taken before the broken unit flees. The Boar Riders roll a total of 9 which is more than their leadership of 7 so they panic. The Goblins roll a remarkable 4, even less than their miserable leadership of 5 which means they bravely stand fast. Both the Orcs and the Boar riders will flee away from their enemy who may well pursue and attempt to destroy them. Note that a unit that panics and flees from hand-to hand fighting does not lead to further panic tests - only units that are defeated and break in combat cause panic tests.
For example: A unit of 10 Elves is charged in the flank by a unit of 5 Wolf Riders while fighting a unit of Goblins to its front. The Elves take a panic test as soon as the Wolf Riders declare their charge and are found to be within range. The Elves roll a total of 10 which is more than their leadership of 8 so they panic and flee. The Elves flee 2D6" away from their enemy (their movement is less than 6" so they always flee 2D6"). The Goblins are already fighting the Elves and so may pursue. The Wolf Riders continue their charge to its maximum distance, in the same way as if their foe had decided to flee voluntarily.