The CHARIOT System, acronym meaning "Combat History and Refined Implementation of Tactics", and also referred as Chariot Tarot, is a gameplay mechanic introduced in the PSP version of Tactics Ogre: Let Us Cling Together.
The CHARIOT System first becomes available after the tutorial battles. It works differently than the other tarot cards. Instead of selecting it from your inventory or picking one up on the battlefield, you simply press the L shoulder button of the PSP during one of your unit's turns.
Pressing the L shoulder button brings up a menu on the left-hand side of the screen which displays the portraits of all units on the battlefield, including guests. You can select any character and their action will play back on the main screen.
Pressing X on the character's portrait will rewind the battle to that point. Once you have gone back in time to a previous action, the CHARIOT menu will split off into an alternate timeline. You can then rewind again to any point, and the menu will reflect the different actions you have taken.
If you repeat the same actions, the timeline will not split, and you can use the Chariot Tarot as many times during any battle you wish; it displays the last 50 actions you and your enemies have taken.
Although not out-right explained, you can lose out on certain titles if you use the Chariot Tarot even once. The amount of victories without using the Chariot Tarot is displayed in the battle results page of the Warren Report.