And so you aren't chained by the Solar Charm structure, because that's what Mirror does.
When it's a case of the Charms doing the same type of thing, and the ones using them are altered Solars, then Mirror's copying of Charm structure makes sense. Training Charms have little reason to use a different Charm tree structure outside of 'Oh, these aren't Solars,' even though a core part of Abyssal fluff is that they are, in fact, twisted Solars, who sometimes use twisted Solar Charms. When you are copying a piece of a Charm set entirely, with minor mechanics differences on a Charm-by-Charm basis, then Mirror makes sense.
I want to see Mirror for direct equivalent Charm trees and sections of Charm trees like the training and basic 'cores' of Charm trees, things that have no particular need for a different layout from the Solar version because they do the same thing in a slightly different way. And if you give Abyssals some sort of bizarre nonsense, Solars should already have or get a variety of tangentially-related thing.
But Lunars have a monopoly on combat shapeshifting
No, it's that due to being the splat for shapeshifters they should be the best at it, if only by being more flexible. The Abyssal version should all be focused on the nightmarish monstrosity able and willing to kill entire cities, with little to no capacity outside of that. Except
maybe turning into mist or a moving shadow. Those should be Necromancy things, though. Remember, Necromancy isn't just for making the dead come up to serve you or messing with ghosts, it's supposed to be a death-and-entropy focused counterpart to Sorcery. So, all those bizarre effects that have nothing to do with anything Solars or canon Abyssals have should be considered as a Necromancy option.
They don't get to stop the Chosen of Death turning into horrible killing monsters that look like hungry ghosts, shadows covered in eyes, giant vampire bats and big spectral hounds.
I'm fine with that, as long as it's objectively worse than the Lunar equivalent at doing some of the same things and gets access to some weird tricks that the Lunar version doesn't that make it more useful in different things. It should be less versatile and capable of the Lunar playstyle support, because it's being used by a dedicated murder monster.
And, separated from the rest, I reiterate: If an effect you want these Abyssals to have doesn't fit with the core of 'death, decay and entropy' thematics, consider sticking it in Necromancy. Remember, a lot of things Vampires do in a lot of settings comes from learning dark magic. As does literally everything every form of lich in every setting ever can pull. And Necromancy is lacking in the bullshit hax of Sorcery, even though the two are meant to be counterparts. Seriously, most of this stuff you people are suggesting fits in with Necromancy as Sorcery for murderbeasts, soul binders and other nasty magic archetypes.
