Seeing Orochimaru ease his suppression of the First, Second, and Fourth Hokage and start egging them on to attack her, Karin would have been lying if she said she wasn't nervous.
It was true that Orochimaru was a traitor to Konoha, but it was also true that she wanted the half of the Nine-Tails inside the Fourth Hokage. So there was no way she could explain to the three Hokage that she actually belonged to Breaking Dawn and had nothing to do with those lunatics from the Dark Dawn.
So she didn't try to defend herself. She stayed silent.
But that very silence made the three Hokage sense that something was wrong.
As far as the three Hokage knew, no ninja in the Shinobi World could face them so calmly. And their side had Orochimaru and Sage Kabuto, too.
Their silence had undoubtedly confirmed what Orochimaru had just said: their opponent had come for the Nine-Tails inside the Fourth Hokage.
The Second said to the First, "Big Brother, we can't let that organization get its hands on the Nine-Tails!"
"Mm." The First nodded, then said to the Second and Fourth, "Our opponent has mastered Wood Release. Be careful."
"Yes!"
The Second and Fourth answered respectfully.
After warning the Second and Fourth, the First stepped forward and called out, "If you leave now, you can avoid a fight!"
Karin remained unmoved, cheering herself on inwardly. They're just Impure World Bodies. There's nothing to be afraid of!
"Ah!"
The First sighed and clapped his hands together.
In an instant, amid a thunderous roar and the trembling earth, countless vines burst from the ground and grew wildly.
"Is this the First's true Wood Release?"
Kabuto Yakushi was taken aback.
With his consciousness restored, the First's Wood Release was more than twice as vast