Please PEACH. This is only a first draft, never tested, conceived in a single journey from home to university. The numbers could be all wrong and make the game unplayable; however ff the system can work, I'm willing to change them.
With great power comes great responsibility
This is an alternative magic system I've been thinking about lately, after reading this thread.
Basically this system is a combination of the Recharge magic variant from UA and the fluff of the Ambient energy variant suggested in the aforementioned thread. The rules for casting spells are the same of the Recharge magic variant, with the difference that the recharge time a specific recharge spell becomes instead the casting time of said spell (i.e. Disguise self requires 4 hours to be cast).
The Recharge magic system is otherwise unaffected. And here comes the Ambient energy variant: whenever casting a spell a caster draws energy from a pool of mana, and each level of spells has its own cost; the pool is linked to a determined extension of space, measuring 100ft x 100ft x 100ft, called from now on Mana Pool Area (MPA): each MPA can provide only a limited amount of magical energy before being depleted; moreover, the amount of energy each caster can draw in any single casting is limited: if too much mana is drawn for a single spell, the strain on the MPA could be unbearable and mishaps could occur.
Mechanically, each MPA has 4 relevant values that must be considered: a Lower Threshold (LT), an Upper Threshold (UT), a Soft Limit (SL) and an Hard Limit (HL). Both the Thresholds govern the amount of energy a caster can draw in a single casting; the Limits are instead linked to the maximum amount of energy that can be absorbed from each MPA.
Lower Threshold: spells with a cost lower than the LT can be cast without any problem. Spells with a cost greater than the LT strain the MPA, risking to cause a minor energy surge.
Upper Threshold: spells with a cost greater than the UT inevitabily cause a Major Energy Surge, as the energy drawn is too much to be channeled safely.
Soft Limit: the MPA can safely provide this amount of energy, but casters can try to draw more than this value. When the SL (but not the HL)is reached, every spell cast increases the chance to cause a Major Energy Surge.
Hard Limit: when the MPA has provided this amount of energy, it is exhaust. Magic wielders cannot cast any more spells from their daily allotment until the MPA recharges back. It takes 24 for a MPA to recharge its energy pool, unless it has become a Dead magic zone.
Each MPA can fall in one of three types: Low Magic, Normal Magic and High Magic zones:
Every spellcaster can instinctively "feel" which type of MPA is into; by making a DC 15 Spellcraft check as a swift action, he can determine how many magic points have been drawn from a particular MPA (in game terms he knows the amount of magic points in the Usage Pool).
Each spell costs a particular amount of mana to be cast: the costs are given in the following table:
The magic point cost is that of the effective spell level used, so a metamagic version of one spell costs more, accordingly to the final spell level.
Every time a spell is cast, first compare its cost to the LT: if the cost is lower than the LT nothing happens and the spell is fired normally, with the ususal effects; if the cost is greater than the LT there's a chance of a Minor Surge. Roll a d100: if the outcome is >= than the difference between the cost and the LT, the spell works normally; otherwise, roll a random effect on the Wild magic table and the caster suffers Nd4 damage, where N is the level of the spell he was trying to cast (Fort negates, DC 15+N).
If the cost is not only greater than the LT, but also greater than the UT then a Major Energy Surge is triggered: the energies channeled cause too much strain on the MPA and lash out destructively and in a more lasting way. Roll a d100 and consult the Major Energy Surge table (see below).
The sum of the costs of all the spells cast in a certain MPA is the Usage Pool (UP). The MPA can safely provide energy until the Soft Limit is reached. When a spell is cast whose cost would make the UP exceed the SL roll a d100: if the outcome is >= than the difference between the UP and the, then the spell is cast normally; however, magical energies begin to resonate in the area, and everybody is aware that the MPA is reaching its limits. If the d100 roll is not sufficient, a Major Surge is triggered: roll a d100 and consult the following table (again, N is the level of the spell that triggered the surge; the DCs for the saves are 20+N):
The air is filled with magic energy but nothing strange happens
For 1d4 rounds, spells cast in the area do not function; any material components are used up
For 1d4 rounds, spells cast in the area function normally but any material components are not used up
A Reverse gravity effect covers all the area for 2d10 hours
Magic jolts fill the area: everyone is blinded, deafened and muted for 2d6 rounds (Fort negates, but a separate ST is required for every condition)
Everybody in the area suffers Nd10 damage (Fort halves)
Everybody in the area suffers Nd4 damage/round for 1d4+1 rounds (Fort negates, one save each round)
Spells cast in the area are maximized for 1d4 rounds, as for the Maximize spell feat; they do not use more magic points; if the spell is already maximized there is no further effect
Spells cast in the area are empowered for 1d4 rounds, as for the Empower spell feat; they do not use more magic points; if the spell is already empowered there is no further effect
The entire area is struck by an earthquake as per the Earthquake spell
All the magical properties of any magic item in the area are temporarily negated for 2d4 rounds (no save)
The entire area is struck by a Storm of Vengeance spell that lasts 10 rounds
1d3 monsters are summoned near the caster who caused the surge, as per the Summon monster N spell; the monsters immediately attack a random target
A rip to the Astral plane opens within 10' from the caster: everything in a radius of 100' from the rift is sucked into it and cast on the Astral plane (Ref negates)
A rip to a random plane opens within 10' from the caster: everything in a radius of 100' from the rift is sucked into it and cast on a random plane (Ref negates)
Negative energy surges in the area: everyone is subjected to Nd8 damage from negative energy (undead are instead cured) (Fort halves)
Positive energy surges in the area: everyone is healed from Nd8 damage from positive energy (undead are instead damaged) (Fort halves)
For 2d4 rounds, spells cast in the area require additional 1d20 magic points to be cast
The area becomes a Wild magic zone for 1d10 rounds
The area becomes a Dead magic zone for 1d10 rounds
For 1d4 rounds spells cast in the area produce only illusory and quasi-real effects: targets are allowed a Will save to disbelieve each effect; they can voluntarily fail a save
Every spellcaster must succeed in a Will save or be struck by a Feeblemind spell
For 1d4*10 minutes the area is subject to the combined effect of Solid fog and Magic fog spells; neither spell allows a saving throw
The area permanently becomes a Wild magic zone
The area permanently becomes a Dead magic zone
Example: A Wizard and a Cleric are battling an enemy Sorcerer in a completely charged Normal Magic area. The LT for this zone is 25 and the UT is 62, which means that every spell whose level is 5th or less can be cast without problems (as the cost of 5th level spells is 20 magic points, less than the LT), 6th level spells have a 5% chance to trigger a Minor Surge, 7th level have a 17% chance, 8th level have a 31% chance and 9th level have a 47% chance of minor surging; moreover, 9th level spells cast in the MPA automatically collapse a Major Energy Surge, as they cost 72 magic points and the UT is 62.
In the first round, the Wizard casts a 7th level spell: he draws the needed energy, as the air ripples with raw power. Since the spell costs 42 MP, the DM rolls 1d100 to check for Minor Surges, but the Wizard is lucky and nothing happens; 42 MP are added to the Usage Value, and since the MPA has a SL of 250 magic points it can fuel the spell without problems.
The Cleric follows casting a 6th level spell: the cost for this spell is 30 MP, greater than the LT, so another Minor Surge roll is needed; the Cleric is lucky too, and the spell works normally. The UP is increased by 30 MP, for a value of 72 MP.
Finally, the Sorcerer casts a 7th level spell: the DM rolls for Minor Surge and also the Sorc is lucky. The UP reaches 114 MP.
In the second round, the Wizard casts a 4th level spell: since its cost is lesser than the LT no roll is needed and the spell is cast without problems. The UP is at 126.
The Cleric decides to push the bounds casting an 8th level spell: this spell requires a Minor Surge roll by the DM, and since the cost is 56 MP against a LT of 25, the chances of the surge are 31%. This time the Cleric isn't lucky: a Minor Surge is triggered, the Clerics suffers 6d4 damage from the magic energy unleashed (his save fails) and the roll for the random effect indicates that the spell doesn't function but it's components are used. Crap! The UP rises to 182 MP.
The Sorcerer laughs and casts an 8th level spell: the DM rolls for Minor Surge, again 31%, and the Sorc is lucky. The UP goes up to 238, dramatically close to the Soft Limit.
In the third round, the Wizard decides to gauge the MPA: he makes the Spellcraft check and discovers that only 12 MP divide the UP from the Soft Limit. Any spell of level higher than the 4th have a chance to trigger a Major Surge! He decides to take the risk and casts a 6th level spell: its cost is greater than the LT, so the DM rolls for Minor Surge, but luckily nothing happens. Now the UP is at 268, 18 MP over the Soft Limit: the DM rolls for the Major Surge at 18% and luckily nothing happens.
The Cleric, noticing the jolts of magic power in the area, understands that the MPA is under heavy strain and decides to cast a low level spell not to risk a major collapse: he casts a 3rd level spell, so no check for Minor Surges, but the UP goes to 274 MP. The DM checks for Major Surges, at 24%, and luckily again, nothing happens.
The Sorcerer, being in difficulty, decides to push the hand: he casts a 9th level spell! Since the cost of the spell, 72 MP, is greater than the Upper Threshold of 62 MP, a Major Surge is automatically triggered; more, the spell has a 47% chance to trigger a Minor Surge; more and more, the cost of the spell brings the UP to 346 MP, which means that the roll for Major Surge would be at 96%! The DM rolls the d100 for the Minor Surge and the Sorc is unlucky; then the DM rolls the d100 for the Major Surge and, again, the Sorc is unlucky! Which means that the Sorcerer is struck by a Minor Surge, and the entire MPA is struck by 2 Major Surges! The result of the Minor Surge is the Glitterdust effect; the first Major Surge is a surge of negative energy which deals 9d8 damage to everyone in the 100x100x100 area; the second Major Surge is the Feeblemind effect. Everyone makes the saves for the negative energy and for the Feeblemind, and the poor Sorcerer fails the second, becoming easy target for the Wizard and the Cleric.
The final value of the UP is 346, meaning that 3rd level spells or greater cannot be cast, as the UP would exceed the Hard Limit. After 24 hours the MPA resets its UP, and new spells can be cast in it.
You can draw a smaller amount of MP to cast a spell. Benefit: each spell cast costs 3 MP less. Special: You can gain Accomplished caster multiple times. Its effects stack.
Attune Mana Pool Area
Universal Level: Brd 5, Clr 6, Drd 6, Sor/Wiz 6 Components: V, S, M Casting Time: 24 hours Range: Close (25 ft. + 5 ft./2 levels) Area: one 100ft cube (or standard dimension of an MPA) Duration: 100 days Saving Throw: No (harmless) Spell Resistance: No
This spell modifies the properties of a specific Mana Pool Area to suit the needs for spellcasting of a particular class of magic wielders. On casting the spell, the caster chooses a particular individual or group, an alignment or faith, or spell school, subschool or descriptor: for the spells that match the description, the Lower Threshold and the Upper Thresold doubled.
Example: a pyromaniac Wizard living in a Normal Magic area decides that in his tower he doesn't want to be hampered casting high level spells with the Fire descriptor. He then casts Attune Mana Pool Area and chooses the Fire descriptor: the LT and UT for Fire spells become 50 and 124, while for the other spells remain at 25 and 62.
No more than one Attune Mana Pool Area can be active at every moment on a single area.
Material components: magical tools and incenses worth at least 5000 gp.
Improve Mana Pool Area
Universal Level: Brd 3, Clr 5, Drd 5, Sor/Wiz 5 Components: V, S, M Casting Time: 24 hours Range: Close (25 ft. + 5 ft./2 levels) Area: one 100ft cube (or standard dimension of an MPA) Duration: 100 days Saving Throw: No (harmless) Spell Resistance: No
This spell increases the type of a Mana Pool Area to the following type; thus a Low Magic area becomes Normal, and a Normal Magic area become High: the change affect both the Thresholds and the Limits. If the spell is cast on a High Magic area it only raises its Lower Threshold and Upper Threshold by 10 points.
No more than one Improve Mana Pool Area can be active at every moment on a single area.
Material components: magical tools and incenses worth at least 4000 gp.
The Pearls of Power work in a slightly different way: each Pearl can grant a number of temporary MP to the wielder, allowing him to draw power from these points instead than from the MPA. The points granted by each Pearl fade after 1d4+X rounds, where X is the level of the Pearl used. A caster can use the Pearls when casting spells with long casting times (the Specific recharge spells) using the Pearls in the final moments of the rituals.
Crown of Lucky Castings
The wearer of this crown can decide to neutralize the chance to cause a Minor or Major Energy Surge when casting a spell that normally would carry this chance. For example, when casting a 6th level spell in a Low Magic area there is a 15% chance to trigger a Minor Surge: by using the Crown the caster can neutralize this chance, thus casting the spell safely.
The Crown has another use: when casting a spell whose cost is greater than the Upper Threshold (that is, a spell that has 100% chance to collapse a Major Surge), the wearer can force a roll for the Major Surge with the same chance of the Minor Surge. For example, casting an 8th level spell in a Low Magic area has a 41% chance to cause a Minor Surge and automatically causes a Major Surge: by using the Crown, the Wearer can decide not to suffer automatically the Major Surge, but to check it with the same probability of the Minor Surge, that is 41%.
The Crown can be used once per day, regardless of the function invoked.
Strong transmutation; CL 14th; Craft Wondrous Item; Price 110,000 gp
Goggles of Mana Gauging
The wearer of these goggles can determine as a free action the class of a MPA and the amount fo MP in its Usage Pool.
A Magic Enhancer is a massive pyramidal structure covered in strange runes and dotted with resonant crystals. The structure enhances the magical properties of an area of 2000ft x 2000ft x 2000 ft, centered on the Enchancer itself: the Magic Pool Areas covered by the effect of a Magic Enhancer are treated as being one type better than they are; High Magic zones have their Lower Threshold and Upper Threshold increased by 10.
Strong transmutation; CL 17th; Craft Wondrous Item, Improve Mana Pool Area; Price 200,000 gp