My subsystem ideas

[Morphic tide]

Sorry, what is upcasting?

It's that thing in 5th edition D&D where you can cast a spell at a higher level that it's default for increased effect.

[Morphic tide]

Another idea, this time less a proper subsystem and more a shorthand for meta-classes with fiddly multi-competencies and ability stealing, as well as PRC progressions that have need of progressing a wide variety of classes.

Associations; What Are They, What They Are Meant To Be Used For, Why Have Them?:
As the name suggests for people with a long-ass memory of things on this forum, this is based on the Trissociate build-a-class setup from 2012. Unlike that, this has actual base classes and the subsystem being planned here is more about centralizing a major list causing function. The intended use is mainly for feature-swapping, but continuing progression of specific features throughout PRCs is another use case, killing off rules exploits from Legacy Champion and Uncanney Trickster style PRCs. It also works for when you have features that need all "classy" functions, but be below the power of actual classes players would use, like the Splitsoul.

The reason to have them is simple: Kill off repetitive lists. If your class has direct feature copying, an Association can be used to limit the features and adjust them to be mechanically acceptable. If the class swaps features that are nearly identical to existing classes, then it can instead use Associations to streamline any sliding scale involved.

Mechanics of the Subsystem:
First off, it's actually more in line with Splitsoul's mechanics than Trissociate's, with each Association being a partial class in its own right. Generally t4 or t5 if used alone due to tight focus, unless its a particular subset of caster or something that has innate tiering problems like Conjurers or, potentially, Crusaders, and that's more on the brokenness/inherent flexibility of the topic. In the cases where the topic of casting is fundamentally broken, like Conjuration, it gets reduced in progression or is solely the subset of casting with some token focusing on a subset within it. Or a restricted possible list to relevel and exclude problem spells.

Accessing association levels will come with two numbers: Total Association Level and Maximum Association Level. The former will frequently be larger than one's actual level, while the latter will always be lower. How much varies, but the gist of it is that level appropriate abilities come from overlapping Associations. Multiple spellcasting associations to get level-appropriate spellcasting with multiple, though narrow, "topics", multiple precision damage associations to get to the 1/2 level d6s, multiple Rage-carrying Associations to get level-appropriate usefulness and so on.

The "partial class" thing would be taken further than Trissociate's Associations, but not quite as far as Splitsoul. Not sure if the full chassis would be present, though Splitsoul style use would necessitate it, the point is to have a streamlining of all the ability carry over present in the ruleset without exhaustive per-class lists or piles of specification clauses. In general, the mechanical limits to it make it so it'd need to be run by ratios, with the soft upper limit on the Maximum Association Level being whatever amount is needed for the "strong" progressions to max out at the standard class's strong progressions. For example, if Associations cap out at 2/3 BAB, then the soft upper limit is one-and-a-half Association Levels per class level. Mathematically, the general ratio will probably be decided by receprical of what I want the Associations to cap out at. Then bonuses come to make up for some of the deficiency where needed, like an automatic Weapon Focus chain on the weapon-focused version of the Fighter-type Association. The same could be made to apply to subsystem progressions, as well, to utterly remove overspeed progression.