Så här har jag löst det i Generica (sorry för att tabellerna ser lite skumma ut, exemplen hamnade mitt i texten och att kapitälerna blev fel):
5.2.3 Limits of magic casting
There need to be some limit to the use of magic or it will lose its mystery and just become a full auto combat weapon. The following sections describe what these limits are and what happens if you pass them.
5.2.3.1 The Mana Tally
Magic is not an unlimited resource, it stretches reality around the magician and if reality is stretched too far, it may snap back or break, which potentially dangerous results.
To keep track of how much reality is strained, the MANA TALLY is used. The MANA TALLY starts at zero and is increased each time the magician uses magic. The mana cost of spells depends on the spell level used, calculated as spell level squared. Spectacular successes counts as one level lower, spectacular failures as one level higher.
Spell level Mana cost
0 (only possible through spectacular success) 0
1 1
2 4
3 9
4 16
5 25
6 (only possible through spectacular failure) 36
The game master may also lower the mana cost if the magician takes great care to avoid affecting reality too much, for example by using gentle and discreet magic to influence key events.
5.2.3.2 Magic backlash
Each magician has a SAFE MANA LIMIT. As long as their MANA TALLY does not exceed this limit, there will be no problems. Once this limit is crossed, however strange things may start to happen.
The SAFE MANA LIMIT is calculated as follows (truncate any fractions):
(Highest arcana x (Intelligence + Mental Strength + Knowledge) / 2) + additional arcana levels
Hawk has level 3 mastery of air, level 1 mastery of fire and level 2 mastery of metamagic. His INTELLIGENCE is 14, his MENTAL STRENGTH is 15 and his KNOWLEDGE is 13. This gives him a SAFE MANA LIMIT of 65 (calculated as (3x(14+15+13)/2)+1+2).
Whenever a spell is cast resulting in a Mana Tally exceeding the Safe Mana Limit, roll on the magic backlash table. Make one die roll for each started ten points above the SAFE MANA LIMIT. If results that are opposites are rolled and a sensible explanation can?t be found, reroll the lowest.
D100 Backlash result
1 Massive weirdness, the game master decides.
2 ? 19 No effect.
20 ? 21 Magician looses contact with the magic and magic does not work for the entire day.
22 ? 23 Magician is shaken, will have nightmares for days and will not be able to sleep well during that time.
24 ? 25 Magician temporarily gains a mental disadvantage, at random or chosen by the game master. It will gradually disappear during the following weeks.
26 ? 27 Magician temporarily gains a physical disadvantage, at random or chosen by the game master. It will gradually disappear during the following weeks.
28 ? 29 Magician temporarily get one random stat halved. It will return at a rate of one per day.
30 ? 31 Magician cannot cast spells for D10 days.
32 ? 33 Magician cannot cast spells for D10 days. Others will have their effective arcana mastery lowered by 2 when near him for the same duration. He will not be popular with other mages.
34 ? 35 Magician cannot cast spells for D10 days. Others will have an additional +10 difficulty when casting spells when near him for the same duration. He will not be popular with other mages.
36 ? 37 Magician cannot cast spells for D10 days. Others will have to make a single roll on the backlash table when casting spells when near him for the same duration. He will not be popular with other mages.
38 ? 39 Magician will have to make an extra backlash roll when casting spells for the next D10 days, even if one is normally not needed.
40 ? 41 Magician cannot recharge mana for D10 days.
42 ? 43 Magician cannot recharge mana for D10 days and neither can anyone in his vicinity.
44 ? 45 The area where the spell was cast becomes a magic super node for D10 hours. All spells can be cast as if they were one level lower.
46 The area where the spell was cast becomes a magic super node for D10 days. All spells can be cast as if they were one level lower. Other mages will swarm to the place.
47 ? 48 The area where the spell was cast becomes drained of magic for D10 hours. All spells can be cast as if they were one level higher.
49 ? 50 The area where the spell was cast becomes drained of magic for D10 days. All spells can be cast as if they were one level higher.
51 The area where the spell was cast becomes drained of magic permanently. All spells can be cast as if they were one level higher.
52 ? 53 The area where the spell was cast becomes a magic sinkhole for D10 hours. No spells can be cast there.
54 ? 55 The area where the spell was cast becomes a magic sinkhole for D10 days. No spells can be cast there.
56 The area where the spell was cast becomes a magic sinkhole permanently. No spells can be cast there.
57 ? 58 Magician suffers nausea and headaches.
59 ? 60 Magician knocked out (spell level x3L).
61 ? 62 Magician injured (spell level x2D).
63 ? 64 Magician severely injured (spell level x3D).
65 ? 66 Magician is visually affected for hours. He may look like he is on fire, he may be crackling with energy or some other effect at the game masters discretion.
67 ? 68 Mana tally is lowered to half its current value. Magician is aware of a change, but it will take days before he knows how much and in which direction.
69 ? 70 Mana tally is doubled. Magician is aware of a change, but it will take days before he knows how much and in which direction.
71 ? 72 Mana tally is tripled. Magician is aware of a change, but it will take days before he knows how much and in which direction.
73 ? 74 Magic works, but at a very reduced power. A fireball becomes a firecracker and so on.
75 ? 76 Magic works, but power is greatly increased. Trying to knock an enemy off his feet with a blast of air will knock him straight through the house behind him and level the house.
77 ? 78 Magic works, but will not turn off (the game master decides how long it will last). A magician reading a persons mind will not be able to stop and will be locked in there until rescued or the game master decides he has had enough.
79 ? 80 Magic has random effect, but weak.
81 ? 82 Magic has random effect.
83 Magic has random effect, with power greatly increased.
84 Magic has random effect and can?t be turned off.
85 ? 86 Magic has opposite effect, but weak.
87 ? 88 Magic has opposite effect.
89 Magic has opposite effect, with power greatly increased.
90 Magic has opposite effect and can?t be turned off.
91 Magic starts a chain reaction, slowly spreading across the land until a magician can halt it with the same spell, an opposing spell or metamagic spell of at least the same level as the original spell. Even beneficial magic will go wrong, healing magic can cause flesh to grow into weird shapes or cause spontaneous pregnancies and so on.
92 ? 93 A tear in reality allows a minor creature (ghost, minor demon) from another plane to slip through.
94 A tear in reality allows multiple minor creatures from another plane to slip through.
95 A tear in reality allows a creature (demon, angel) from another plane to slip through.
96 A tear in reality allows multiple creatures from another plane to slip through.
97 A tear in reality allows a major creature (demon lord, half god) from another plane to slip through.
98 Roll again, but result applies to the closest person.
99 Roll again, but result applies to a random person nearby.
100 Roll again, but result applies to everybody nearby.
In most cases, do not tell the player the exact nature of what is happening. He may get an overall feeling of what has changed, but no details.
As you see, it is quite possible for a magician to go above the SAFE MANA LIMIT, but it is not safe. In some cases, however, it is still the safest alternative.
Our intrepid air warlock Hawk has put himself in a bad position. He has already reached 64 on his MANA TALLY, when he has to use a level 3 spell, bringing the MANA TALLY up to 73 (8 above the SAFE MANA LIMIT). He makes a roll on the backlash table, rolling a 68. His powerful gust of wind is reduced to a mere puff. Desperate, he tries again, bringing the MANA TALLY up to 82, 17 above the SAFE MANA LIMIT. He has to roll twice and rolls 47 and 60. His spell is successful, but he is thrown to the ground unconscious with strange winds tearing at his hair and clothes, but leaving the surroundings untouched.
5.2.3.3 Recharging
Recharging is the process of lowering the mana tally.
There are many different methods of recharging, depending on which arcana the magician is focused on, the type of magician and the personality of the magician. The suggestions listed along the arcana are indications of what a typical master of each arcana might use. They are, however, only suggestions and it is up to the player and the game master to make the final decision on what best suits the character.
Since some activities are easier than others, some guidelines are needed. The basic assumption is that should take two weeks to reduce the MANA TALLY from SAFE MANA LIMIT to zero. This means that if it is an activity that can easily be made daily, it should reduce it by 1/14 of the SAFE MANA LIMIT.
Some advantages and disadvantages may change this by requiring special circumstances or increase or decrease the rate of recharge.
A priest of Ra might recharge when he is praying in a temple of Ra when the sun is shining. This is a CONDITIONAL MANA RECHARGE.
A druid may recharge by performing a ritual at full moon, which is a SLOW MANA RECHARGE.
A fire warlock might choose to recharge by playing with a fire, something that can easily be done under most circumstances. This is normal recharge, unless he takes FAST MANA RECHARGE, in which case he will recharge at twice normal rate, 1/7 of the SAFE MANA LIMIT.
A female shaman of a barbarian tribe may have her mana recharge coupled to her menstrual cycle, having the mana tally reduced to zero once a month. This is a SLOW MANA RECHARGE combined with COMPLETE MANA RECHARGE and AUTOMATIC MANA RECHARGE RITUAL.
Once again, we look at our air warlock, Hawk. After some discussions with the game master, the player decides that Hawk recharges by flying a kite, a suitable choice for an air warlock with kite building as hobby. He also wants to use more spells, so he wants to recharge faster.
The game master decides that suitable conditions for kite flying occur on the average once a week (the game will take place in a mainly forest covered inland area). This means that Hawk will need the FAST MANA RECHARGE advantage and will recharge half his SAFE MANA LIMIT each time he spends time flying with his kite. A kite is not considered a very special item, so it does not count as a disadvantage.
