Brainwashing, a Magic Card also used in the game, can take control of an opponent's Monster with just a cost of 800 LP, and was once considered a Forbidden Card that would lock you up for life. However, after its nerf in 2017, it was released from its ban.
But even aside from the animation, in the real-world environment during the GX era, Brainwashing wasn't banned. This card was imprisoned in 2010, which was already in the late Yu-Gi-Oh! 5D's era.
[Yugen, LP 4000→LP 3200]
Without further ado, Yugen naturally chose the opponent's White Bone King. The White Bone King monster on the opponent's field was once again bewildered by the brainwashing effect and unwittingly came to Yugen's field.
The eyes of the White Bone King on the other side seemed to be glaring to the point of cracking. If there's anything worse than having your Tamashi taken over during a card game, it might just be having your own self taken over...
But that's not all.
"Of course, I don't have 'White Bone' in my graveyard, so even if the White Bone King comes to my field, its Attack Power is just a useless 0."
Yugen said calmly.
"So I'm going to use the 'White Bone King' as a sacrifice for an Upper-level Summon!
Appear, Level Six—
—Chaos Mage, Summon!"
The mighty King of White Bones was reduced to golden light and disappeared upon arriving on his field, and all the bone towers collapsed with a clatter. A vortex of magic power rose to the sky. A magic staff cut through the cyclone of magic, and the Chaos Mage made a splendid entrance.
[Chaos Mage, Attack Power 2400]
"Direct attack by the Chaos Mage!"
The light sphere of Chaos Magic Power erupted from the magic staff, exploding in the face of the White Bone King, causing the skeleton to stagger back, black smoke emanating from its robe.
The White Bone King staggered to steady itself: "Ugh, damn it..."
[White Bone King, LP 4000→LP 1600]
"Then cover two cards, end round."
"Don't be so smug so soon, for I am the King of White Bones! I am immortal!"
The White Bone King stood upright.
"My turn, draw card!
Activate the Magic Card 'Pot of Magic Book,' both players draw three cards from their decks."
The White Bone King drew cards from the deck.
"Then the Magic Card 'Phoenix God's Feather,' discard one card to return a card from the graveyard to the top of the deck. I discard one card to return 'White Bone King' from the graveyard to the deck!
Then activate the effect of 'Prince White Bone' in the graveyard!
Exclude 'Prince White Bone' and two other White Bone cards from the game from the graveyard to Special Summon the returned 'White Bone King' from the deck!
I exclude from the game from the graveyard the Prince, a White Bone, and a Lady White Bone!"
Prince White Bone, a White Bone, and Lady White Bone dissolved into black mist together, creating a swirling vortex of darkness. A tremendous energy burst forth from it, bone towers shot up into the sky, and the ruler of White Bones descended once more!
[White Bone King, Attack Power?]
"With three fewer White Bones in my graveyard, but the card I just discarded is another 'White Bone Princess.' So the number of White Bones in my graveyard is ten.
Therefore, the Attack Power of my avatar becomes..."
[White Bone King, Attack Power 10000]
The skeletal soldiers below the altar: "Easily reached ten thousand Attack Power again!"
"As expected of Lord White Bone King!"
"These sacrifices stand no chance!"
"..."
"It's not over yet." The White Bone King stared intently at Yugen.
It realized now that this sacrifice was different from others. In just a few rounds of play, its avatar had been turned twice, which was extremely insulting.
It always felt as if this person "was more interested in its body than winning the duel."
Such a shocking quirk meant it had to be on guard.
"You seem a bit different from other sacrifices." The White Bone King said ominously, "But the outcome will be no different. I have defeated countless foes, climbed mountains of corpses and endless bones to reach my current position.
What I've been through far surpasses your imagination!"
Originally, it was not born a king, just one among numerous common skeletal monsters.
But it endured hardships, trained with top Fighting Masters, and fought in countless undead wars. It was defeated, it fell, but it always rose again in the end.
It finally defeated everyone's enemies, emerged from seas of blood and mountains of corpses, ascended from an ordinary roadside bone to become a king, and even married its beloved Lady.
It is the king among skeletons, the ruler of this undead territory!
It would never allow anyone to humiliate it like this, especially not on its own turf!
"Activate the effect of 'Bone Nightmare' from hand!"
The White Bone King directly sent a card from its hand to the graveyard with a booming voice.
"By discarding this card from hand, Special Summon an 'Lady White Bone' excluded from the game!
Therefore, I call upon the queen of the skeletal world, my beloved —
— Lady White Bone, Summon!"
An entrance with a skeletal head, but with a touch of aristocratic demeanor in its outfit.
One wonders if a gentleman could ever find a skeleton captivating...
[Lady White Bone, Defense Power 2200]
The debuting Lady White Bone coldly observed the situation on the field.
"Does my presence remain necessary." Lady White Bone said indifferently.
"Haha, yes, I still need the Lady's power." The White Bone King laughed, "Now that the Lady is here, I am invincible!
As long as 'Lady White Bone' exists on the field, all Undead Race monsters, besides 'Lady White Bone,' of Level 3 or below won't be destroyed by battle, nor will they be affected by any Magic or Traps!"
Lady White Bone's ability activated, endowing an invisible resistance to the White Bone King with invisible undead magic, swirling between those two white bones seemingly.
"Now those petty tricks of yours are useless!" The White Bone King roared angrily, "Moreover, due to 'Bone Nightmare' being discarded to the graveyard, the number of White Bones in the graveyard has increased, boosting my Attack Power yet again!"
[White Bone King, Attack Power 10000→Attack Power 11000]
"This strike will end it all!
Attack 'Chaos Mage' with my avatar, 'White Bone King'!"
"Activate the covered card, Continuous Trap 'Soul Barrier.'" Yugen's backfield card flipped over. "As long as there is a monster on my field, the battle damage to the controller of this card becomes 0."
The Chaos Mage endured the heavy attack of the White Bone King, its body exploding, but the released energy did not dissipate, instead forming a soul barrier that stood in front of Yugen. The impact of the undead magic spread close along the trap's protective layer, failing to inflict any substantial impact.
"Tch, barely surviving another round by relying on trap defenses, so I end my turn."
"Then at your end phase, I activate the trap 'Bursting Ambush,' paying 2000 life points to Special Summon a monster from my graveyard in face-down defense position."
I use the card discarded by 'Angel's Charity'..."
[Yugen, LP 3200→LP 1200]
Yugen revealed a card returned from the graveyard.
"Cover with 'Dark Spirit Master: Dark' in face-down defense position."
A covered Monster Card surfaced in his front field.
"Still just setting defensive traps?" The White Bone King sneered, "Well, it seems your only option under our perfect partnership as a couple.
With the Lady by my side, I have no weaknesses..."
"My turn." Yugen pointed to the covered monster on the field, "Flip Summon the covered 'Dark Spirit Master: Dark,' Flip Effect activates, allowing me to gain control of one Dark Attribute monster on your field.
I will take control of 'Lady White Bone.'
The White Bone King began to roll up its sleeves: "Damn it, I'll fight you to the end..."