Chronicle Magician

If a monster(s) with 2500 original ATK or DEF is Normal or Special Summoned to your field (except during the Damage Step): You can Special Summon this card from your hand in Defense Position. If this card is Special Summoned: You can target 1 "Dark Magician" or "Blue-Eyes White Dragon" in your Monster Zone; it gains 2500 ATK/DEF until the end of this turn. You can only use each effect of "Chronicle Magician" once per turn.