The Soul Charge is a move used to increase the power of a character for a short period of time. To do so leaves the character vulnerable to attack while he or she performs the charge, so to successfully complete the Soul Charge, the player must create an opening.
In Soulcalibur II, the Soul Charge was a three-part process, based on the amount of time the command was held for. The duration of the increased power was a function of this. With a character's standard weapon, the Soul Charge could increase the power of a move; for example, Nightmare's Sky Uppercut attack was granted the Guard Break ability when used in conjunction with a Soul Charge. However, many weapons also featured additional attributes when the Soul Charge was used with them, such as a speed or damage increase.
In Soulcalibur VI, the Soul Charge has been reworked into a super mode of sorts, granting the user enhanced fighting ability with either their body or weapon glowing at the cost of a single gauge. Some characters also gain unique abilities, extra attacks or transform entirely while in this state.
In Soulcalibur III, Guard Break Attacks become Unblockable when used in Soul Charge in some occasions