You can Ritual Summon this card with "Chaos Form". This card's name becomes "Dark Magician" while on the field or in the GY. Once per turn, when a Spell/Trap Card or effect is activated (Quick Effect): You can target 1 card on the field; destroy it. If this Ritual Summoned card is destroyed by battle or card effect: You can Special Summon 1 "Chaos" or "Black Luster Soldier" Ritual Monster from your hand, except "Magician of Chaos", ignoring its Summoning conditions.
"Dark Magician" + 1 Warrior monster Gains 100 ATK for each Spell/Trap on the field and in the GYs. If this card attacks a Defense Position monster, inflict piercing battle damage. When a card or effect is activated that targets a card on the field (Quick Effect): You can discard 1 card; negate the activation, and if you do, destroy it.
If your opponent controls more monsters than you do, you can Normal Summon this card without Tributing. If this card is Tributed: You can Special Summon 1 "Black Luster Soldier" monster from your hand or Graveyard. You can only use this effect of "Arisen Gaia the Fierce Knight" once per turn. When you Ritual Summon a "Black Luster Soldier" monster, you can banish this card from your Graveyard as 1 of the monsters required for the Ritual Summon.
If this card is Normal or Special Summoned: You can discard 1 card; add 1 "Polymerization" Normal Spell Card or "Fusion" Normal Spell Card from your Deck to your hand. You can reveal 1 Fusion Monster in your Extra Deck; Special Summon 1 of the Fusion Materials whose name is specifically listed on that monster from your GY, in face-down Defense Position. You can only use each effect of "Keeper of Dragon Magic" once per turn. You cannot Special Summon monsters from the Extra Deck, except Fusion Monsters, the turn you activate either of this card's effects.
This card can be used to Ritual Summon any "Chaos" or "Black Luster Soldier" Ritual Monster. You must also Tribute monsters from your hand or field and/or banish "Blue-Eyes White Dragon" or "Dark Magician" from your Graveyard, whose total Levels exactly equal the Level of the "Chaos" or "Black Luster Soldier" Ritual Monster you Ritual Summon.