After absorbing every last bit of mana from the last mana stone that Arvin had, he felt like his body will explode from all this pain. Excessive mana stored inside his heart wanted to get free from these shackles. But Arvin had closed all the possible ways for mana to escape out of his heart.
While Arvin was lost in meditation, the shield that he was sitting on was boiling the water around him. Slowly and steadily the shield was melting down due to the rune formation. The metal that this shield was made of was never meant to be used in rune formation. Loki chose this shield only because it was bulky and fat enough that melting it with rune formation would take enough time for Arvin to finish his breakthrough.
