Elemental Hero Core, when calculating battle damage, its attack power doubles, which means its attack power can be considered as 5400 points. Solving it through battle might be a bit difficult.
But it's not necessarily solved by battle.
"My turn." Youyu revealed the card he drew, "Magic Card 'Book of Magic in the Pot', both players draw three cards from their decks."
Youyu glanced at the cards and immediately inserted two of them into the Duel Disc.
"Set two cards on the field, then it's the Magic Card 'Gift of the Heavenly Treasure', draw cards from the deck until both hands are replenished to six cards."
After refilling to six cards in hand, Youyu promptly selected one card to discard to the graveyard.
"Effect of Chocolate Magician Girl, once per turn, discard one card and draw one card from the deck." Youyu replaced another card in his hand, then revealed one of them.
"I use 'Chocolate Magician Girl' as a tribute for a Tribute Summon!
Heir to Black Magic, great disciple of the Dark Magician—
—Dark Magician Girl, Summon!"
The chocolate girl flapped her little wings, waved her small hand like she was saying goodbye. She soon disappeared from the field, and a black magic circle spun open, a blonde girl with slender waist, long legs, and spectacular chest flew out gracefully, waving a small heart with her magic staff in mid-air.
[Dark Magician Girl, Attack Power 2000]
"Since there's a 'Dark Magician' resting in the graveyard, Dark Magician Girl's attack power increases by 300."
[Dark Magician Girl, Attack Power 2000 → Attack Power 2300]
Hibiki Koyo said, "Even so, the attack power is still no match for Elemental Hero Core..."
"I know, and I don't plan to win in that way." Youyu raised a card in his hand, "Activate Magic Card 'Timaeus the Knight of Destiny'!
Send 'Dark Magician Girl' on the field to the graveyard, Special Summon a Fusion Monster using her as Fusion Material!"
The magic card held high above his head released a dazzling golden light, as if some great being was summoned through this card as a medium.
It was a transparent dragon, its powerful body covered in indestructible scales, with a single eye rippling with golden light, like sunshine cast on a calm lake.
"The great magician's disciple will don the knight's armor, summoning limitless possibilities by combining with the power of the Legendary Dragon and Black Magic!
Fusion Summon! Appear in a new form—
—Dark Magician Girl the Dragon Knight!"
The Legendary Dragon spun in mid-air, forming a golden vortex. The Magician Girl flew in effortlessly, a burst of tremendous energy exploded downward, landing with the mighty knight.
The dragon's claws stirred up dust on the ground, the silver-armored girl straddled the back of the Legendary Dragon, wielding a silver longsword and an embossed shield.
[Dark Magician Girl the Dragon Knight, Attack Power 2600]
The girl on the dragon's back lightly swung her longsword, the Sword Qi merged with the dragon's might forming a whirlwind-like domain, though vastly different in attack value, it showed no weakness in momentum compared to Elemental Hero Core in front!
"Effect of Dark Magician Girl the Dragon Knight," Youyu said, "once per turn, discard one card, destroy one face-up card on the field!"
Youyu discarded a card to the graveyard.
"Destroy 'Elemental Hero Core'!"
Timaeus roared angrily, the girl looked serious, puffed her pink cheeks, the knight's sword was raised high above her head, with the swirling Sword Qi shooting skyward.
"Flip the Set Card!" Hibiki Koyo responded in time, "Continuous Trap - Dimension Guardian! This trap can protect one of your attack-position monsters on the field, preventing that monster from being destroyed by battle or effect!
I use this card to protect 'Elemental Hero Core' from destruction!"
The trap's defense formed an impenetrable barrier, like a layer of transparent shield.
Dark Magician Girl the Dragon Knight slashed down with her sword, the Sword Qi and the milky impact from the dragon's mouth merged, crashing onto Elemental Hero Core's body like a flood, but was all deflected by the invisible barrier.
"Looks like your strategy didn't work out smoothly." Hibiki Koyo said.
Youyu remained unfazed, "Then I activate the effect of 'Vision Hero Faris' in my hand, discard one 'Hero' monster in my hand for a special summon.
I discard 'Elemental Hero Shadow Mist', to special summon Faris!"
[Vision Hero Faris, Attack Power 1600]
"Effect of Shadow Mist, when discarded to the graveyard, add a 'Hero' monster from the deck to the hand." Youyu revealed the card drawn from the deck, "I add 'Elemental Hero Airman' to my hand.
Next is the effect of 'Vision Hero Faris', which, when summoned, places a 'Vision Hero' card from the deck on the field as a trap card.
"I'll place 'Vision Hero Poisoner'!"
A dark phantom appeared in Youyu's backfield, a hero's blurred outline.
"'Poisoner's' effect, it can special summon by sacrificing a 'Hero' monster on your field." Youyu waved his hand grandly, "Sacrificing 'Vision Hero Faris', special summon 'Vision Hero Poisoner'!"
[Vision Hero Poisoner, ATK 900]
"Poisoner's effect," Youyu continued, "when summoned from the trap zone, it halves the attack power of one monster on the field! Halve the attack power of 'Elemental Hero Core'!"
Poisoner, standing firm, shot without glancing. A purplish-black beam bullet shot out from his pistol, piercing through Core's armor. The toxin spread rapidly, like purplish-black vines crawling all over the Elemental Hero's body.
[Elemental Hero Core, ATK 2700 → ATK 1350]
Hibiki Koyo frowned, "Is the target Core's attack power?"
Even when under brain control, he couldn't help but admire this Duel King senior from the heart.
Using the power of the Legendary Dragon "Timaeus the Knight of Destiny" for a strong attack, and swiftly launching an effective and fierce offensive from a new blind spot after being defended...
"But 'Elemental Hero Core's' attack power doubles during battle." Hibiki Koyo said, "Even if halved, its attack power will still reach 2700 during battle. Dark Magician Girl the Dragon Knight's strength is still insufficient to..."
"I know."
As they spoke, a card popped out from Youyu's graveyard.
"When I activated 'Mask Change II' last turn, I discarded this card to the graveyard." Youyu revealed that card, "Destiny Hero Malicious!"
Hibiki Koyo's eyes flickered.
Malicious? That card was...
"Banish 'Destiny Hero Malicious' from the graveyard to special summon another card with the same name from the deck! Come, Destiny Hero Malicious!"
[Destiny Hero Malicious, ATK 800]
"Next, activate the magic card 'Fusion Substitute'!" Youyu said, "Fuse 'Vision Hero Poisoner' and 'Destiny Hero Malicious' on the field!
Fusion requirements are two 'Hero' monsters! Fusion summon—
—Vision Hero Trinity!"
The fusion of Destiny and Vision heroes, a hefty energy pillar burst from the vortex! As if from overlapping phantoms, a solid form gradually appeared, a hero landed dominantly, black ribbons swirling, he crossed his arms, shattering the exhibition hall floor beneath his boots.
[Vision Hero Trinity, ATK 2800]
Hibiki Koyo clenched his teeth.
Exceeding the doubled attack power of Core, huh?
"And once again activate the effect of 'Destiny Hero Malicious' from the graveyard, to banish it and special summon another card with the same name!"
[Destiny Hero Malicious, DEF 800]
"Trinity's effect!" Youyu said, "Once per turn, target a monster on the opponent's field and a 'Hero' on your field to activate, decreasing the opponent's monster's attack power by the attack power of your 'Hero' until the end of the turn!
So I will decrease 'Elemental Hero Core's' attack power by Malicious's attack power—800 points!"
Trinity uncrossed his arms, raised a large hand with a "rise" gesture, the black ribbon fluctuated with the turbulence. The explosive shockwave instantly locked onto Core, the Elemental Hero was engulfed by the skyward light pillar, his abilities greatly suppressed.
[Elemental Hero Core, ATK 1350 → ATK 550]
Hibiki Koyo's expression changed a bit.
On the surface, it seemed like only 800 ATK was reduced, but considering Core's attack power doubles during battle, factually it was a reduction of 1600 ATK!
If Trinity attacks now, even with Core's effect boosting it, his max attack power would merely reach a pitiful 1100.
Though protected by the trap effect of "Dimension Guardian," making Core unable to be destroyed by battle or effects, Youyu doesn't need to destroy anything at this moment.
With Trinity's attack, Hibiki Koyo, with only 1600 Life Points remaining, will meet direct defeat!
"Battle!" Youyu had already commanded, "Vision Hero Trinity, attack 'Elemental Hero Core'! Ambition penalty!!!"