"Theseus, what are you doing here?" asked Newt in dismay.
"That is no way to greet your valiant rescuer!" Theseus replied. By the way, it turns out Theseus later becomes Crookshanks. This is canon now.
Anyway, Theseus turned his wand on Grindelwald and boldly proclaimed, "Stand aside, foul villain!"
"I will not!" said Grindelwald, raising his wand.
"And he's not a villain either!" added Credence. "I'll have you know that Grindelwald is actually nice!"
"This wicked villain has hoodwinked you!" declared Theseus. "Come with me to freedom!"
"No, I won't let you trick me!" said Credence, raising his wand as well.
And with that, all three of them began to fight. Or more precisely, Grindelwald and Theseus fought while Credence stood awkwardly off to the side, waiting for a chance to get in a curse. Newt ran to Tina and unchained her.
"We've got to get out of here!" he told her.
"But we don't have our wands," said Tina.
"Never mind that now," said Newt. "We've got to do what we can to help Jacob!"
Unarmed but unafraid, Newt and Tina bolted heroically for the door.