This card can work great in decks that use lots of flip-effect monsters, as you can Special Summon them face-down. Another idea is to play "Soul Reversal" to bring "Spear Cretin" to the top of your deck, providing defense for one turn, and bringing back a flip effect monster from the graveyard.
Use with "Needle Worm" to chew through your opponent's deck and Hand.
Another one is to use "Waboku" if this card was attacked (no need to use this if this card remains face-down during your next turn), when this effect resolves, you can use "Crush Card Virus", it will not just destroy all monsters on the field with 1500 ATK above it will also give you an advantage with this card's effect only.
Use with "Cyber Jar" to clear your opponent's field.