Possible solutions

In the end, he meditated for a minute to gather enough mana to open and close the exit. Rain sighed in relief when that happened, but instead of stopping to rest due to the lack of mana, he just grabbed the huge block of earth that kept his father sealed and began to carry it.

"I Need to hurry," Rain thought. "I need to escape this area as soon as possible…"

Rain could easily be found during the day carrying his father, but he didn't have any other choice. He still had his potions left, so he could use them in case of emergency to escape. For now, the best solution to undo the brainwashing was to keep his father as far away as possible from the caster.

"... It seems that the area around is clear," Rain thought while looking around when he reached the end of the tunnel.