Strain

Strain Based Mana System

Terminology
Mana: You have a pool of this. Casting spells drains from the pool.
Strain Tolerance: This is mana by a different name. Instead of counting mana down, casters accumulate strain points, and have a limit on how many they can accumulate. This is a purely cosmetic change — people, generally, have an easier and faster time using addition (counting strain up from 0 to an upper bound) than subtraction (counting mana down to 0 from a pool) — this can easily be inverted with no mechanical change.
Mana/Strain Cost: This table shows us the mana or strain cost (the costs are identical) of each spell. As you can see, the cost increases slightly with spell level (duh) but decreases with caster level – this is the most important feature of the system, the concept that finally made mana-based casting a real and balanced option.

The Rules
From here on out, the rules are described in terms of strain instead of mana, due to addition being a faster mental process than subtraction. All rules that are not specified (such as the difficulty classes of spells) are the same as in the core rules.

Strain Tolerance
Your strain tolerance is equal to your primary casting stats divided by 3 (the actual stat, not the stat modifier) times 2.8. You also gain additional Strain Tolerance equal to ½ your level in spellcasting classes and prestige classes that add to your caster level.

Casting a Spell
When a mana-based Weave Mage/Sorcerer 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 Weave Mage/Sorcerer can cast without resting. Every spell has a Strain Cost, which depends on the level of the spell and the level of the Weave Mage/Sorcerer, as shown on the tables below. At high class levels, some spells have no Strain Cost, and this is fine – a powerful Weave Mage/Sorcerer can cast basic spells all day long.

Whenever a Weave Mage/Sorcerer 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 Weave Mage/Sorcerer has accumulated is lower than her Strain Tolerance, a Weave Mage/Sorcerer suffers no ill effect. Continuing to cast spells once her Strain is over her Tolerance, however, is extremely taxing on a Weave Mage/Sorcerer’s body and mind.
As soon as a Weave Mage/Sorcerer’s total Strain exceeds her Tolerance, she becomes fatigued (even if she is normally immune to this condition; this is fatigue of the mind, not the body). If a fatigued Weave Mage/Sorcerer wishes to cast another spell, she must first make a 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 Weave Mage/Sorcerer casts the spell as normal. If the save is failed, the spell fizzles with no effect and the Weave Mage/Sorcerer becomes exhausted (even if she is normally immune to this condition). An exhausted Weave Mage/Sorcerer may not cast any more spells. A Weave Mage/Sorcerer ceases to be exhausted after an hour of complete rest. (Note: The DC on the Fortitude save can and should be changed based on specific classes — I’d imagine Sorcerers would have lower saves, for example.)

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 Weave Mage/Sorcerer has the available Strain to do so. The advantage that mana-based Sorcerers should have over mana-based Wizards is amount of Strain available.

Recovering Strain
A Weave Mage/Sorcerer loses Strain equal to ½ her character level, minimum 1 (but never more than her casting stat modifier) per hour if she does not cast spells, fight, run, or otherwise exert herself. A Weave Mage/Sorcerer who is fatigued due to excess Strain ceases to be fatigued as soon as her total Strain is no longer over her Tolerance. However, a Weave Mage/Sorcerer does not recover Strain while exhausted.
A Weave Mage/Sorcerer recovers from Strain much faster when she rests. A full 8 hours of rest completely removes all Strain.

Example: The Weave Mage/Sorcerer
The Weave Mage/Sorcerer ready spells each day in the same fashion as their Wizard cousins, but cast from Strain/Mana instead. As noted under Casting a Spell, they do not lose prepared spells once they cast them — instead, their spells are limited by their available Strain.

Level Strain Cost
0 1st 2nd 3rd 4th 5th 6th 7th 8th 9th
1st 7 8 — — — — — — — —
2nd 5 7 — — — — — — — —
3rd 4 6 8 — — — — — — —
4th 3 5 7 — — — — — — —
5th 2 4 6 8 — — — — — —
6th 1 3 5 7 — — — — — —
7th 0 2 4 6 8 — — — — —
8th 0 2 3 5 7 — — — — —
9th 0 1 2 4 6 8 — — — —
10th 0 1 2 3 5 7 — — — —
11th 0 0 2 2 4 6 9 — — —
12th 0 0 1 2 3 5 8 — — —
13th 0 0 1 2 2 4 7 9 — —
14th 0 0 1 1 2 3 6 8 — —
15th 0 0 0 1 2 2 5 7 9 —
16th 0 0 0 1 1 2 4 6 8 —
17th 0 0 0 0 1 2 3 5 7 9
18th 0 0 0 0 1 1 2 4 6 8
19th 0 0 0 0 0 1 2 3 5 7
20th 0 0 0 0 0 1 2 2 4 6
Table: Weave Mage/Sorcerer Strain Costs

(Special note: feats like Versatile Weave Mage/Sorcerer (RDr) would not allow you to sacrifice level 3 castings for level 4 castings at level 20, because such feats explicitly deal in spell slots and this variant does away with such a concept.)
Example: The Sorcerer
The Sorcerer has an identical table to the Weave Mage. However, he has far more limited spells known than the Weave Mage does. To make up for this limitation, the Sorcerer multiplies his casting stat by 1.5 when calculating his Strain Tolerance. Thus, the Sorcerer can cast more of his limited spell selection than the Weave Mage can cast of her much wider spell selection.

Changing Recovery Mechanics
This system has been designed so that the recovery mechanic can very easily be changed to suit your needs of your game. As written here, the system covers fatigue-based casting, recharge magic and, finally, a full recovery on rest for those who still believe in the 4-encounter work day. I expect most people to use the system exactly as written, but it has been engineered to be easy to add and remove these or other components to provide the recovery mechanic you want for your own game.

For an example let’s say you don’t like the recharge component as written, which allows you to recharge more strain and cast more of your higher-level spells as your caster level goes up. I believe this to be a good feature, but some will dislike the power curve it introduces to Weave Mage/Sorcerers. To change this to better suit your needs, you can remove the current recharge mechanic and replace it with the following: You recover one-quarter your total strain every hour (but never more than your casting stat modifier). This divorces caster level from recovery and thus guarantees that a high-level Weave Mage/Sorcerer can’t cast more of his top-level spells in a day than a low-level Weave Mage/Sorcerer can.

Strain

Toril 2011 ajenn