Why not.

[Cutmaster]

I. Forbidden Cards

You cannot use these cards in your Deck or Side Deck:

BLACK LUSTER SOLDIER - ENVOY OF THE BEGINNING
BREAKER THE MAGICAL WARRIOR
BUTTERFLY DAGGER - ELMA
CHANGE OF HEART
CHAOS EMPEROR DRAGON - ENVOY OF THE END
CHAOS SORCERER
CYBER JAR
CYBER-STEIN
DARK HOLE
DELINQUENT DUO
EXCHANGE OF THE SPIRIT
FIBER JAR
GRACEFUL CHARITY
HARPIE'S FEATHER DUSTER
IMPERIAL ORDER
LAST TURN
LAST WILL
MAGICAL SCIENTIST
MAGICIAN OF FAITH
MAKYURA THE DESTRUCTOR
MIRAGE OF NIGHTMARE
MONSTER REBORN
PAINFUL CHOICE
POT OF GREED
RAIGEKI
SINISTER SERPENT
THE FORCEFUL SENTRY
THOUSAND-EYES RESTRICT
TIME SEAL
TRIBE-INFECTING VIRUS
TSUKUYOMI
VICTORY DRAGON
WITCH OF THE BLACK FOREST
YATA-GARASU

NEW! - Snatch Steal, Ring Of Destruction


II. Limited Cards

You can ONLY use one of the following cards in the Deck & Side Deck combined:

BOOK OF MOON
CALL OF THE HAUNTED
CARD DESTRUCTION
CEASEFIRE
CHAIN STRIKE
CONFISCATION
CRUSH CARD VIRUS
D. D. WARRIOR LADY
DARK MAGICIAN OF CHAOS
DIMENSION FUSION
ELEMENTAL HERO STRATOS
EXODIA THE FORBIDDEN ONE
FUTURE FUSION
GIANT TRUNADE
GRAVITY BIND
HEAVY STORM
JINZO
LEFT ARM OF THE FORBIDDEN ONE
LEFT LEG OF THE FORBIDDEN ONE
LEVEL LIMIT - AREA B
LIMITER REMOVAL
MAGE POWER
MAGIC CYLINDER
MIND CRUSH
MIRROR FORCE
MORPHING JAR
MYSTICAL SPACE TYPHOON
NEO-SPACIAN GRAND MOLE
NIGHT ASSAILANT
NOBLEMAN OF CROSSOUT
OVERLOAD FUSION
POT OF AVARICE
PREMATURE BURIAL
PROTECTOR OF THE SANCTUARY
RIGHT ARM OF THE FORBIDDEN ONE
RIGHT LEG OF THE FORBIDDEN ONE
RING OF DESTRUCTION
SANGAN
SCAPEGOAT
SNATCH STEAL
SPIRIT REAPER
SWORDS OF REVEALING LIGHT
TORRENTIAL TRIBUTE
TREEBORN FROG
TWIN-HEADED BEHEMOTH
ULTIMATE OFFERING
UNITED WE STAND

NEW! - Demise, King Of Armageddon, Breaker The Magical Warrior, Destiny Draw

III. Semi-Limited Cards

You can ONLY use two of the following cards in the Deck & Side Deck combined:

APPRENTICE MAGICIAN
CREATURE SWAP
D. D. ASSAILANT
DECK DEVASTATION VIRUS
GOOD GOBLIN HOUSEKEEPING
MANTICORE OF DARKNESS
MASK OF DARKNESS
METAMORPHOSIS
RECKLESS GREED
REINFORCEMENT OF THE ARMY
WALL OF REVEALING LIGHT

NEW! - Scapegoat, Destiny Hero Disk Commander, Advanced Ritual Art, Book of Moon, Twin-Headed Behemoth.

[Mike]

Decent BanList. Here are my changes.

I. Forbidden Cards
Add Treeborn Frog to the list. Reason is because it will pretty much make Monarch decks consistently weaker in conjunction to tribute summon a Monarch at +1 advantage.

II. Limited Cards
Nothing, restricting Demise to one is perfectly okay, Breaker being unbanned is fine too, since the banning of Snatch is there, and lastly, restricting Draw is good, since DDT, T.dek/PC/PC Monarchs always run three Draw, restricting it to one prevents some inconsistent usage of cards that combo well together in deck.
Add Reinforement of the Army to the list. Reason is because it's pretty broken when your opponent as no backrow, you'd Rota for LV2, or nothing when you get hit by Don.
Add Cyber Dragon to the list. UDE has made this card's efficient usage major. Everyone runs three, no matter what. It's broken how you can special such a creature, and ram though so much. Limiting it to one will stop that good topdeck, and limit the chance of having it opening hand.
Unban MoF. With Snatch and broken cards gone, we can see Apprentice more with Phoenix, eh? Unban Tsukyomi. No reason, we can't limit every broken card.

III. Semi-Limited Cards
Scapegoat is fine at two. Asura might so more play now. No need to even restrict Disk at all, putting it to two is pointless, since everyone uses one. Putting Advanced Art at two is pointless, as Demise is at one, keeping Art at three is fine. Book at two is fine. Behemoth is pointless at two, keep it at three, no one will use more than one.

Other than that, read and take my suggestions to this banlist within reason and take my opinions into the current/future metagame!

[The Quiff]

You cannot unrestrict Twin-Headed Behemoth. Unfortunately, the wording on it makes it impossible to know, should you have more than one copy, which one has used the effect.