The Eye of Timaeus (DRLG-EN005) - Dragons of Legend Unlimited

(This card is also always treated as "Legendary Dragon Timaeus".)
Target 1 "Dark Magician" monster you control; Fusion Summon 1 Fusion Monster from your Extra Deck that lists that monster on the field as a Fusion Material Monster, using it as the Fusion Material. You can only activate 1 "The Eye of Timaeus" per turn.