Critical Hits are a random occurrence in Yggdra Union. When a unit charges another, there is a chance that they will land a critical, taking out the head and causing the opponent to go into a state of panic. This greatly debilitates the victim, as they will no longer be able to fight aggressively or use skills, on top of the disadvantage of not being able to counter, and losing several soldiers upon being charged; under the right conditions, a critical can occasionally wipe out the entire unit in the initial charge. If the enemies aren't knocked out upon the assault, they panic for a couple of seconds; the time varies. The LUK stat is very influential in scoring criticals, as they can make them easier to land, as well as make it more difficult for the enemy to land one on the unit. Lastly, criticals add bonus damage to the total Morale damage, making them very devastating; lethal in many cases.
There are equippable items in the game that can increase the critical rate of the attacker by 50%, as well as items that can prevent criticals from landing, or even make it easier to get criticaled. Also, some items negate the panic time that occurs upon taking a critical blow.