“Wind-Up” is an archetype of mostly monsters with effects that can be used only once while they are face-up on the field—this is the reason why a lot of their support cards revolve around flipping them face-down (Legendary Wind-Up Key) or returning them to the hand (Overwind).
“Wind-Up” monsters may not see much play in the near future due to their own nature: they were designed primarily for Xyz Summoning and that is the reason why cards such as Wind-Up Soldier and Wind-Up Warrior focus on Level manipulation.
This deck centers around Overwind, a Trap Card that can double the ATK and DEF of a “Wind-Up” monster, but that also forces you to return it to the hand in the End Phase, and Drowning Mirror Force, which can make up for this drawback of the latter.
Once, while Wind-Up Juggler is face-up on the field, after damage calculation, you can destroy a monster it battles with; Wind-Up Juggler can essentially be used to get rid of any monster you can't get over naturally.
Wind-Up Knight, similarly to XX-Saber Fulhelmknight, can negate an opponent's attack with its effect, but it can only be used once while it's face-up on the field and your opponent must be targeting a “Wind-Up” monster for you to activate Wind-Up Knight's effect; since it's not stated otherwise, you can activate Wind-Up Knight's effect even if it's the one being targeted for the attack.
During the Main Phase, you can increase the Level of Wind-Up Soldier by 1 and its ATK by 400 until the End Phase, making it reach 4400 ATK with Overwind; much like the others, you can only used this effect once while Wind-Up Soldier is face-up on the field.
Overwind is pretty straight forward, it doubles the ATK and DEF of a “Wind-Up” monster, usually putting them above anything that isn't a Silent Magician LV8, but it returns that monsters to the hand during the End Phase. Thanks to Drowning Mirror Force you can leave your field empty relatively safely after using this card and Endless Trap Hell also allows you to recycle it.
This Skill is commonly used in Trap-heavy decks, it allows you to recycle Overwind while also preventing you from decking out.