"So you dodged Granmarg's effect," T-Bone said. "But that leaves you with only two sets.
I now activate the Spell 'Card of Heaven and Earth' from my hand.
In a turn I have performed a Tribute Summon, draw 2 cards from the Deck. However, cards drawn this way cannot be used this turn, and if they can be Set, at least one must be Set before the end of the turn."
T-Bone drew 2.
"Continuous Trap 'Appropriate'," Kira said. "Since you drew outside the Draw Phase, I draw 2."
Kira also drew 2.
"Next, the effect of 'The Rock Spirit' in my hand," said T-Bone. "'The Rock Spirit' is a Level 4 that cannot be Normal Summoned; it can only be Special Summoned by banishing an EARTH monster from the GY."
A golden light flared from his GY; he showed the banished card and slipped it into the deck box.
"I banish the EARTH 'Mine Golem' from my GY to Special Summon 'The Rock Spirit'!"
An armored giant with a great axe appeared. His skin was like bedrock, the axe whooshing through the air.
[The Rock Spirit, ATK 1700]
"Battle phase," T-Bone said. "'The Rock Spirit', attack 'Don Zaloog'!"
The spirit closed in, bellowed, and hacked down. Don Zaloog crossed his arms, but the heavy blow cleaved through; he flew back like a cut kite, retreating miserably.
[Kira, LP 2500 → LP 2200]
"Boss!"
"Boss, you okay?!"
Zaloog, now a spirit after leaving the field, tumbled among his teammates. The Dark Scorpions hurried to help him up.
"Cough, I'm fine—dammit," Zaloog gritted his teeth. "Got careless."
"Next, the Monarch attacks!" T-Bone declared. "Granmarg, attack 'Dark Scorpion - Meanae the Thorn'!"
The mighty Monarch closed in, a golden fist blasting forward!
But at the instant the blow landed, Meanae suddenly detonated early in a strange way. A mass of drifting red substance spread from the blast, creeping over Granmarg, engulfing him completely—until he was gone.
T-Bone: "!"
What was that?
"When Meanae is destroyed by battle, the virus using her as a medium triggers."
Kira smiled and pointed at his backrow.
"Trap Card 'Crush Card Virus'.
When a DARK monster with 1000 ATK or less you control is destroyed by battle, activate: destroy all monsters with 1500 or more ATK in your opponent's hand, field, and Deck!" (anime/original effect)
T-Bone's pupils contracted; his heart skipped a beat.
What, what, what!?
All monsters with 1500+ ATK—that means—
"Exactly," Kira chuckled. "All 1500+ ATK monsters—including your Monarchs—will exit the stage right here."
Yes—Kira chose Kaiba's original anime version of Crush Card Virus, not the later errata'd TCG/OCG version.
As said before, he considers both versions to have pros and cons. The anime version is excellent against certain opponents, but can backfire badly against others.
Sending all 1500+ ATK monsters from the opponent's Deck to the GY obviously risks feeding them tons of resources.
But against this opponent, it's ideal—because Kira knew he was facing "Monarchs."
The famous Monarchs are all 2400 ATK—well within 1500+. More importantly, Monarch is a Tribute Summon deck whose effects trigger on Tribute Summon.
In other words, if he nukes all Monarchs from the deck to the GY, the opponent can't Tribute Summon them. Even if they do revive a Monarch from the GY, it's just a 2400 beatstick with no effect—most of the threat is gone.
Monarchs that can't be Tribute Summoned don't get effects—like a tiger with its fangs pulled, no threat at all.
T-Bone clearly realized the severity.
Eyes wide, he watched the virus devour his two on-field monsters, then savagely spread over his Deck, yanking the Four Monarchs out one by one.
"No!"
"My Monarchs—my power—don't—"
"Yamero!!!"
No matter how he screamed, nothing changed. All the Monarchs were consumed before his eyes, ground to dust, and scattered to the wind.
"Of course, when your Rock monsters are destroyed, in theory 'Guidance to Ore' can Special Summon same-named monsters from the Deck," Kira smiled. "But your same-named targets just got blown from the Deck to the GY, so there's nothing to summon."
T-Bone: "..."
"You're running pure Monarchs, aren't you?"
Kira grinned.
"So now that you've lost all your Monarchs, how much fight do you have left?"
T-Bone said nothing, but his teeth ground audibly.
He glanced at his hand, thought for a moment, then set two cards.
"I set two and end."
Though dire, his eyes were resolute—he hadn't given up.
Kira narrowed his eyes.
So even without Monarchs, he believes his deck can still fight?
Interesting.
"End Phase—flip set card," Kira said. "Trap 'The Deep Grave'.
Choose any monster in either GY. During my next Standby Phase, Special Summon the chosen monster to my field."
T-Bone's face twitched again.
Choose from either GY?
"Right. Your entire 1500+ ATK lineup just went to the GY," Kira smiled. "Which means I can pick any 1500+ ATK monster from your deck's best.
That's a wide selection. Which should I choose..."
T-Bone: "..."
"I'll go with this one."
Kira pointed at the opponent's Duel Disk.
"From your GY, I choose 'Granmarg the Rock Monarch' to Special Summon to my field in my next Standby Phase."
T-Bone: "..."
As noted, Monarchs only trigger when Tribute Summoned. A revival is a Special Summon; even if it hits the field, it's a 2400 vanilla beater.
So any Monarch would do. Kira simply picked Granmarg—after all, it's the opponent's soul card. He might find it more... familiar.
See? He's so happy his face is twitching.