The C.H.A.R.I.O.T Tarot card system is a unique feature introduced 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 during one of your character's turns (not guests).
Pressing the L shoulder button brings up a menu on the left-hand side of the screen which displays the portraits of all characters 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.
C.H.A.R.I.O.T is actually an acronym for 'Combat History and Refined Implementation of Tactics.'
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 at the top of the "Warren Report"