View source for Mana-Based Spellcasting (3.5e Variant Rule)

==== Casting a Spell ====
When a mana-based spellcaster casts a spell, she has to channel a portion of the mana she is using through her own body. This is taxing both physically and mentally, and is the basic limiting factor that determines how many spells a mage can cast without resting. Every spell has a Strain Cost, which depends on the level of the spell and the level of the spellcaster, as shown on the tables below. At high class levels, some spells have no Strain Cost, and this is fine - a powerful spellcaster can cast basic spells all day long.

Whenever a spellcaster casts a spell, she suffers Strain equal to the spell's Strain Cost. As she casts more spells, the Strain accumulates. As long as the total Strain a spellcaster has accumulated is lower than her Strain Tolerance, a spellcaster suffers no ill effect. Continuing to cast spells once her Strain is over her Tolerance, however, is extremely taxing on a spellcaster's body and mind.

When a spellcaster's total Strain exceeds her Tolerance, she is [[SRD:Fatigued|fatigued]] (even if she is normally immune to this condition; this is fatigue of the mind, not the body). If a fatigued spellcaster wishes to cast another spell, she must first make a [[SRD:Fortitude|Fortitude]] save with a DC equal to (20 + the spell's level + the amount of Strain she has over her Tolerance). If the save is successful, the spellcaster casts the spell as normal. If the save is failed, the spell fizzles with no effect and the spellcaster becomes [[SRD:Exhausted|exhausted]] instead of fatigued (even if she is normally immune to this condition). An exhausted spellcaster may not cast any more spells. A spellcaster ceases to be exhausted after an hour of complete rest.

If the spell is cast by a class that would normally ready spells every day, the "readied spell" is not forgotten and can be cast again, as long as the spellcaster has the available Strain to do so. The advantage that mana-based Sorcerers should have over mana-based Wizards is amount of Strain available.
Author	Surgo +
Identifier	3.5e Variant Rule +
Rated By	Leziad +, Foxwarrior +, DanielDraco +, Ganteka Future +, Jota +, Ghostwheel +, Wildmage +, Elohim +, Spanambula +, Enigma + and Franken Kesey +
Rating	Rated 3.3 / 4 +
Title	Mana-Based Spellcasting +