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You can only use each effect of "Myrddin, Sage of the Noble Knights" once per turn. You can discard this card; add 1 "Noble Knight" card from your Deck to your hand. You can target 1 "Noble Knight" monster you control; equip this card from your Graveyard to that target. The equipped monster gains 200 ATK, and it is unaffected by your opponent's Spell/Trap effects. If this card is equipped to a DARK monster, destroy this card. When this card is sent from the field to the Graveyard, except by its own effect: Send 1 "Noble Knight" card or "Lady of the Lake" from your Deck to the Graveyard.

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You can only control 1 face-up "Noble Arms of Sagacity". Equip only to a "Noble Knight" monster. It is unaffected by other card effects. Once per turn: You can target 1 card on the field; destroy 2 Equip Spell Cards you control, and if you do, return that target to the hand. If this face-up card on the field is destroyed and sent to the Graveyard: You can target 1 "Noble Knight" monster you control; equip this card to that target. You can only use this effect of "Noble Arms of Sagacity" once per turn.

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Equip only to a "Noble Knight" monster. It gains 700 ATK. When this card is sent to the Graveyard: You can banish 1 Warrior-Type monster from the Graveyard to target 1 "Noble Knight" monster you control; equip this card to that target. You can discard 1 card, except "Arms of the Noble Knights"; add this card from your Graveyard to your hand. You can banish this card from your Graveyard to target 1 "Noble Arms" Equip Spell Card in your Graveyard; add that target to your hand. You can only use this effect of "Arms of the Noble Knights" once per turn.

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1 Tuner + 1 or more non-Tuner "Noble Knight" monsters
When this card is Synchro Summoned: You can target 1 "Noble Arms" Equip Spell Card in your Graveyard; equip that target to this card. Once per turn: You can target 1 "Noble Arms" Equip Spell Card in your Graveyard; equip that target to this card.

Added the fourth card: Artorigus, Noble Knight of Avalon. Made for my friend (he requests it, and greatly wants it). Originally intended to make cards equipped to it unaffected by opp's cards. But after much thoughts, I dropped that idea, and comes out with what presented there.
Myrddin: Atk/def from 500/500 to 1900/2200. Nerfed its atk+ to 200. Fixed its lore from 'If this card is equipped to a DARK monster, destroy it.' to 'If this card is equipped to a DARK monster, destroy this card.'