Thoughts on a Setting

[Whitewings]

Originally Posted by Varyon

unless Powerstones let you break that limit so long as no more than 1 energy is contributed by you personally

This is correct. Powerstones are usable as normal.

[RGTraynor]

Originally Posted by Varyon

Blowing yourself up with a 1 energy spell seems rather unlikely, although they may experiment with deadly elixirs and the like in an attempt to defeat the current restrictions (much as alchemists poisoned themselves and their clients with "immortality" potions).

This is one of those situations where RAW doesn't emulate the zeitgeist very well, and the OP might resort to a mechanic such as S. John Ross' Unlimited Mana. The trope where desperate researchers undertake dangerous and chancy experiments is what I imagined, and what would fit the situation perfectly.

High investment in single spells may also be a result, as IIRC every +5 to skill above 15 is -1 to energy cost. Shape Earth 20 lets you use Shape Earth on up to 2 cubic yards, Plant Growth 25 allows you to cast the spell, etc. Considering OP has noted that the restriction is per mage rather than per spell, you could still have circles of mages casting some spells by each contributing 1 FP.

Yes, but there are two issues here. The first is that anything-25 represents an enormous investment in time and focus -- in 39 years of play, exactly two PC spellcasters in my campaign ever ran a spell that far, and only with a single one apiece.

The second is the aforementioned "far fewer mages." You might get that single Plant Growth-25 mage in a kingdom. And you might not. You sure as hell won't see twenty mages running spells up to -25 without a RuneQuest-esque level of mage density in the first place, and their services will have a very minimal impact on the setting. One of the hoariest fallacies this forum dives into on a regular basis is conflating "technically possible" into "ubiquitous."

OP has stated the restriction is per mage, and I suspect this would mean Slow and Sure would still be an option (which is 1 energy per mage per day).

I played strict constructionalist on the OP's words "any casting of any spell." Enchantments, officially, are spells. If a mage can only put 1 pt of power into a "spell," that eliminates enchanting. Obviously if the OP didn't mean that to include enchanting, that's another ball of wax.

[Whitewings]

Slow and Sure is possible, and if you have assistants and Powerstones enough, Q&D is also possible.