Tribute "Pot of The Forbidden" to Ritual Summon this card, then Special Summon it during your End Phase. Its Flip Effect will be continuously reuse turn after turn; it can also be flipped face-up in the appropriate moment during your opponent's turn, in order to destroy their monsters or disrupt their future plays by shuffling one of the cards from their hand into the Deck. On the other hand, during your turn, all Spell/Trap Cards can be returned to the hand for safe, effective attacks or simply draw 2 cards to get raw card advantage.
This card can be used in a "Shaddoll" Deck: this card can be Ritual Summoned using "Shaddoll Beast" + a Level 4 "Shaddoll", getting bonuses from their effects in the process. Then this card can be used to continuously revive "Shaddoll" monsters and/or reset their effects, by flipping them face-down.
Although less consistently, this card can also be used in a "Worm" Deck, that also have Flip monsters.
Use this card to spam "Needle Worm" and quickly mill your opponent's Deck.
This card's effect can also be used defensively, by changing to face-down Defense Position an opponent's attacking monster or to protect a monster from cards like "Mirror Force", "Sakuretsu Armor", etc.