There were three skills that Myrene got from the ancient dragon.
First was Clairvoyance. It was more of an ability to see past walls and anything that was hidden from the naked eye. That was why when Myrene entered the room, she could already see the cage. But she didn't react that much.
The second was Heat Resistance. Though she was resistant to heat already due to having her own fire magic, it gave her instead more resistance to heat that could reach 1,170 celsius. The normal temperature of hot boiling lava. However, it didn't mean she could stay longer since it would continuously exhaust her mana.
And the third skill was the Dream Pressure.