The ace card is "The Dark Magicians" who have powerful effects besides "Red-Eyes Dark Dragoon" and "Master of Chaos".
The Key Cards:
1. "Secrets of Dark Magic": A Spell Card for Fusion Summoning monsters that either includes "Dark Magician" or "Dark Magician Girl", such as its ace card.
2. "The Dark Magicians": It has an effect to draw 1 card once per turn when any Spell/Trap is activated and then Set it if it was a Spell/Trap and activate it on the same turn it was Set. Then once it is destroyed, you can retrieve both "Dark Magician" and "Dark Magician" onto your field.