Editing Yagura:SRD:Spellcasting Strain (section)

== Casting a Spell ==

First you must [[Yagura:SRD:Casting_Spells#Choosing_a_Spell|select a spell]] to cast, as normal. If you prepare your spells you may only cast spells which you have prepared. Casting a prepared spell does not make the spell unprepared. If you cast spontaneously you may cast any spell that you know.

When you cast a spell, you have to channel a portion of the magic through your own body. This is taxing both physically and mentally, and is the basic limiting factor that determines how many spells you can cast without resting. Every spell has a strain cost, which depends on the level of the spell and your caster level, as shown on the tables below. At high class levels, some spells have no strain cost, which one would expect - a powerful spellcaster can cast basic spells all day long.

Whenever you cast a spell, you suffer strain equal to the spell's strain cost. As you cast more spells, the strain accumulates. As long your total accumulated strain is lower than your strain tolerance, you suffer no ill effect. Continuing to cast spells once your strain is over your tolerance, however, is extremely taxing on your body and mind.

As soon as your total strain exceeds your tolerance, you become [[Yagura:SRD:Fatigued|fatigued]] (even if you are normally immune to this condition; this is fatigue of the mind, not the body). If while fatigued you wish to cast another spell, you must first make a [[Yagura:SRD:Fortitude|Fortitude]] save with a DC equal to (20 + the spell's level + the amount of strain you have over your tolerance). If the save is successful, you cast the spell as normal. If the save is failed, the spell fizzles with no effect and you become [[Yagura:SRD:Exhausted|exhausted]] (even if you are normally immune to this condition). While exhausted you may not cast any spells. You cease to be exhausted after an hour of complete rest.