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« on: April 27, 2012, 09:28:05 AM »
However you are the dm. If you say the plants in the garden supply oxygen enough for the prisoner then they do. It´s unlikely your players will try to calculate if there are enough plants for it to work in real life.
You could also simply design a creature from the elemental plane of air and say it creates oxygen and is unable to return home do to the no magic or other wards on the prison. It could even be there of its own volition or be a guardian there so if the players kill it they are on the clock for getting away before the air is used up.
Reall as the dm you can pretty much do whatever you want and if the story/adventure is exciting who cares about the physics?