[3.5 core] Fixing allies

[Yitzi]

One of the balance issues in D&D (not a major one, but one significant enough, and different enough from most others, to call for special attention) is that of allies. Even leaving aside stuff like chain-gating solars (which, by the way, doesn't work if the solars don't want to cooperate; Gate provides no special power to overcome their innate Magic Circle against Evil), calling spells potentially allow you to call in allies substantially more powerful than yourself and take credit for them winning the battle for you. Various spells (most notably Charm and Dominate, but potentially also Polymorph Any Object) can also gain allies which can then help you win fights without taking a share of the XP. And then of course there's Leadership...even with its limitations (means CHA can't be a dump stat, need to share equipment or have him get weaker as the levels go on, 2 less level, probably lower ability scores) the cohort still will probably increase effectiveness by at least 30-40%, which is a bit much for a single feat.

So, here's my ideas to fix them:

Calling:

Spoiler

Show

1. A called creature reduces gained XP, calculated as follows:
After winning the fight, calculate (for each party member) the experience gained for defeating every called creature that fought alongside you (as per DMG page 38). If any creature is 8 levels than the party member (and therefore would provide no XP), it doesn't count; if it is 8 levels higher than the party member (and would therefore provide no XP) it counts as infinite. Divide the result by 300 times your ECL. The called creatures count as this portion of a party member when dividing the listed XP by the number of party members to calculate actual XP.
2. A called creature also takes a share of the treasure (above and beyond any spent to gain their aid). For each party member, find (on the table on the DMG p.38) the XP for ECL equal to the encounter level and CR equal to the party member's ECL (in essence, reverse the numbers.) Again, if the ECL is too low for any XP this is 0; if it's too high this is infinite. Then do the same for each called ally (using ECL equal to encounter level and CR equal to the ally's CR). Add all the numbers (for party members and allies) together, and divide each ally's result by this sum. This is the portion of the treasure, by monetary worth, taken by that ally; the party may choose which portion it is (so long as it comes out to the right value.)
If the encounter level is more than the highest-level ally CR or party member ECL by at least 8, then the denominator will be 0, so this method won't work. In such case, the division of treasure, like the XP award, must be determined by the DM.
If the encounter level is less than the highest-level ally CR or party member ECL by at least 8, then the denominator will be infinite, so this method won't work. In such case, all party members and allies with the highest ECL/CR present split the treasure evenly (and, for party members, afterward split it with the entire party.)
3. Called creatures are not PCs, but rather NPCs whom the character has some degree of influence over (depending on the details of the calling spell; in the case of Gate (assuming it's not changed by house rules), they probably might as well be PCs.). (This is actually RAW, and simply is worth re-elaborating.)

Allies gained by other spells:

Spoiler

Show

1. If the spell has duration of at least 24 hours, such allies split XP as described under Calling, but do not split treasure.
2. Allies gained by spells are not PCs, but rather NPCs whom the character has some degree of influence over (depending on the details of the spell; Dominate gives enough influence that they might as well be PCs, Charm Person and Suggestion somewhat less so.) (This is actually RAW, and simply is worth re-elaborating.)

Leadership:

Spoiler

Show

1. The Leadership feat gives followers as described, but does not provide cohorts. There is, however, a new feat, Improved Leadership (prerequisites: Character level 9th, Cha 13, Leadership) that allows you to gain cohorts as described.
2. Cohorts and followers are not PCs, but rather NPCs whom the character has some degree of influence over. (This is actually RAW, and simply is worth re-elaborating.)
3. A leader can choose his cohort's race, primary class, and alignment (subject to DM approval), but no more. He may advise the cohort regarding matters such as feat, skill, and spell choice and multiclassing, but it is the cohort's decision whether to follow the advice. (RAW seems to indicate this anyway, but is not clear.)

Monster abilities:

Spoiler

Show

1. Whenever a creature has a spell-like ability that imitates a spell with variable XP cost, it can only imitate the usage with minimal cost unless the description indicates otherwise.
2. A djinni's Wind Walk and a nightmare's Astral Projection and Etherealness can only target the "caster" themselves.
3. Any ability that cannot be used by a summoned creature also cannot be forced by any means of commanding or controlling a creature. The only exception is a noble djinni granting wishes to its captor; even in such case, the capture must have been by natural means rather than a spell such as Planar Binding.

[Ashtagon]

Or, just treat any ally (whether through Leadership, or through some kind of long-duration summoning/calling effect that lasts at least 10 minutes) as a party member. The ally's level is considered either the same as the average party level, or its own, whichever is higher.

The overall effect is to increase the number of people the XP is divided between, and increase the average party level, making the total XP received lower.

[Yitzi]

The problem with that is that it makes low-level allies have a cost far in excess of the advantage, and a high-level have a cost far less than the advantage. Remember, XP is modified for the number of other party members, but not for their level. What I proposed for everything but leadership is essentially a modification of your idea that compensates for this fact. (Leadership becomes too weak for a feat if it has no XP advantage over an actual new party member...but it's too strong for a single feat if it doesn't, hence requiring 2 feats and a substantial CHA investment.)
Of course, substantial XP penalties without corresponding treasure penalties are an easy way to get a party overpowered for its ECL due to high wealth, so called allies (which, unlike spell-gained allies, can be made to be substantially more powerful than oneself, are relatively easy to get, and in the case of a cleric cannot easily be turned on the party by a clever enemy as a dominated or charmed ally can) have those as well.