"Swallowtail Butterspy" and "Blue Mountain Butterspy".
"Butterspy", known as "Phantom Butterfly Assassin" (
The Deck’s playing style consists of using many strategies to manipulate and weaken enemy's monsters, mainly by changing their Battle Positions and decreasing the opponent's monsters stats. As well as keeping your Life Points safe and maintaining field control by activating spells and traps to change the battle position either on your/opponent's turn. Another way in keeping your Life Points safe would be through Special Summoning monsters from your Deck when one is destroyed and sent to the Graveyard.
With "Moonlit Papillon" being the main searcher of the Deck, you are able to Special Summon any type of "Butterspy" monster from your Deck. "Morpho Butterspy" has its effect only activate when a monster's battle position is changed to either Attack Position or Defense Position which allows you to target that monster thus having it lose 1000 ATK or DEF which would come in very handy by activating "Enemy Controller", "Butterflyoke" and many other battle changing cards. That would give you the upper hand against monsters with high attack or defense. Also protecting your Life Points. With "Swallowtail Butterspy", you can target a monster on the field and lower its attack depending on how many Life Points you have inflicted on your opponent. To get full use of her effect, you can play "Infected Mail" which would be proven useful. But its only an option. "Blue Mountain Butterspy" serves as a "Kagetokage" for the theme, helping it to Xyz quickly into the needed Xyz Monster like "Photon Papilloperative" and "Photon Alexandra Queen".
One of the best and easiest ways to run this Deck is to splash in "Chaos" cards, as most of the archetype is DARK. "Morpho Butterspy", "Swallowtail Butterspy" and "Blue Mountain Butterspy" are DARK while "Moonlit Papillon" is LIGHT. Additionally, playing cards like "Thunder King Rai-Oh" can really mess up your opponent's plays.
The main purpose is to maintain field control while your monsters are sent to the grave and then Special Summoning monsters from your Deck through their effects also getting either "Black Luster Soldier - Envoy of the Beginning" or "Chaos Sorcerer" out on the field and keeping your opponent's monsters off the field as well as protecting your Life Points through changing battle positions. A good card to help start everything off would be "Howling Insect". Despite the fact its an EARTH monster, it can be used as a searcher to help get "Moonlit Papllion" on the field after its destroyed by battle. Then, when its destroyed as well, you can search for a "Butterspy" monster and then Special Summon it. This can be helpful since you are able to Xyz Summon a monster at a much faster rate. You can also run "Effect Veiler" in your Deck to keep your opponent's monsters from activating that would ruin any chance of winning.