Made this thread as a continuation on my thoughts that spawned in this thread.
This is an attempt to "fix" the many issues of Sacred Geometry while still keeping some of the original flavor and power. The two major issues are in my opinion the following:
The drawback of this feat is that you could potentially lose both your spell and actions if you fail the math homework. But while there originally exists a chance that it could be impossible to achieve the right number, it quickly becomes almost certain as you add more d6s with every level. With enough time, you will never (<<1%) fail the test. And there exists calculators online to just make the test for you.
So as a GM if you want to rein in the power of the feat you need to ban outside help and introduce a time limit. Which leads us to issue #2.
Granting in-character power for out-of-character time expenditure/knowledge.
This feat erases the distinction between the character and the player in an almost grossly impressive way. While the effectiveness of your character will always to a degree be decided by how you play them, this feat's power has absolutely nothing to do with your character.
Being gifted in a certain aspect shouldn't be a requirement for your character being gifted in the same aspect.
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You can use your mathematical prowess to add metamagic effects to your spells without using a higher-level spell slot.
Prerequisite(s): Int 13, Knowledge (engineering) 5 ranks
Benefit(s): When you take this feat, select two metamagic feats you do not yet have. When casting a spell, you can perform the steps below to spontaneously apply the effects of either or both of these metamagic feats, as well as any other metamagic feats you have, to the spell without expending a higher-level spell slot.
Once per day as part of a 30 minute ritual that can be combined with spell preparation or the refreshment of your daily allotment of spells, you contemplate the spiritual meaning of geometric shapes and how to harness the innate power that suffuse them. Roll a d6 for every skill rank you possess in Knowledge (engineering) and write down the result. This is your pool of Sacred Insights for the day. Any unused points are lost when you next refresh your daily spells.
When choosing to cast a spell using Sacred Geometry, first determine the effective spell level of the modified spell you are attempting to cast. Then you must spend an equal amount of points from your Sacred Insight pool and perform a 1 minute ritual consisting of mentally aligning the right geometric shapes. At the end of this ritual, you may cast the spell without expending a higher level spell slot. If this ritual is interrupted before completion (treat it as an ongoing casting attempt for concentration DCs) you lose the spent points from your Sacred Insight pool, but not the spell slot.
Alternatively, you may exert great effort to hasten the ritual to be completed in the normal time it would take to cast the spell. This neither requires the 1 minute ritual nor increases the casting time of the spell, but requires you to spent a number of Sacred Insight points equal to the effective spell level squared.
At level 10, 15 and 20, your pool of Sacred Insights increase by +10 points (for a total of +30 at level 20).
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These changes are aimed to kneecap the in-combat spam of Quickened and Maximized spells, introduce a daily limit in a fairly engaging way, and dissuade converting every spell slot into the highest it can be. I'm envisioning this to be used mostly out-of-combat, or to cast lower level spells during combat.
Might have gone a bit overboard with the squared points cost, though.
Not bad, but I don't like the clunky +10 at levels 10, 15 and 20. I'd just allow you to take the feat twice to get extra metamagics and extra Sacred Insight pool. And I'd also give you your Int bonus in SI points (not doubled for two feats).
Squared is rather harsh; you might change it to an additional 1d6 per effective spell level; if you don't have enough, the pool is exhausted and the spell fails and is lost. It means you can do it a couple of times with your better spells if you invest in a rather useless skill.
For example, at 9th level and 24 Int, 9 ranks gives about 28+7=35 SI points. Empowered Fireball (5th) is 5+5d6 is about 22. You can probably still do a Toppling Magic Missile (2 = about 9) or maybe a Persistent Charm Person (3 = about 13) with what's left.
Not bad, but I don't like the clunky +10 at levels 10, 15 and 20. I'd just allow you to take the feat twice to get extra metamagics and extra Sacred Insight pool. And I'd also give you your Int bonus in SI points (not doubled for two feats).
Squared is rather harsh; you might change it to an additional 1d6 per effective spell level; if you don't have enough, the pool is exhausted and the spell fails and is lost. It means you can do it a couple of times with your better spells if you invest in a rather useless skill.
Hm, that's an elegant solution that adds another level of unpredictability. I like it. I might lower it to just 1d6 per spell level to reward the risk taking. That would also thematically imply that taking the time for the ritual means you minimize the amount of points lost.
I choose the +10 increases to make the Sacred Insight pool scale with the highest spell level a wizard could cast, squared. And to add some level of reliability. But that wouldn't be needed with your proposed changes.
I'd add the option to qualify through Profession (Mathematical Philosopher) and Profession (Mathematical Mystic) for any Wis and Cha-based casters that wants to base the pool on Wis/Cha. They still need the 13 Int and invest in even more obscure skills so that seems fair.