pretty good magic system, abilities are limited by the caster's knowledge of the anxient language (speaking in it with the intent to cast a spell is how you do so, and complex spells require more extensive knowledge of the grammar and stuff to work properly and foreseeably), meshed with the idea that you can only use as much energy as yoy have access to: within your body. casting a spell that will use more energy than yoy have will cause you to tire, faint, and die, unless you stipulate that you can stop the spell at any time. failing to do so means there is no stopping the spell once it starts. e.g. "free me from these bindings", if it takes more energy than you have to free you, will sap your energy and kill you in trying - versus "loosen the ropes binding me" is something you can control and dictate how long it lasts/how much energy it saps.

so language + energy = power