If the effect of "Time Wizard" is successful, all monsters on the field are aged. Monsters typically become visibly wrinkled, decayed, and rusted. This results in them becoming much weaker or destroyed.
"Baby Dragon" is the only monster shown to have been positively affected.
"Dark Sage", which was released much later, was given a Summoning method closer to its anime self. It is a Main Deck card, Summoned by Tributing "Dark Magician" after applying the positive effect of "Time Wizard". Unlike its anime self, it is stronger than "Dark Magician" in terms of ATK and DEF. It has a weaker effect than its anime self.
If the player does not have the actual card for the aged counterpart, they can Summon the monster through Fusion Summon. If they have the actual card, they can Summon it normally, without performing a Fusion Summon.
Unlike other media, the younger counterpart, can be one of many cards.