Card evolutions

Retrained is the term used to describe when a monster is reprinted with an new or improved effect. examples include "Battle Ox" to "Enraged Battle Ox" and "Magician of Black Chaos" to "Dark Magician of Chaos".

The term "retrained" comes from "Retrained Elf Swordsman," a possible translation of the Japanese name for "Obnoxious Celtic Guard", who is a retrained version of "Elf Swordsman" ("Celtic Guardian").

Other cards that fit into this catagory are listed below:
 * "Black Luster Soldier" to "Black Luster Soldier - Envoy of the Beginning"
 * "Gaia the Fierce Knight" to "Swift Gaia the Fierce Knight"
 * "Summoned Skull" to "Skull Archfiend of Lightning"
 * "Feral Imp" to "Des Feral Imp"