I'm still reading through it, but this is very good. I especially like the curses. I think the curse declaration method might work for my version of Light Blighting Hate. I'm extra impressed that this is 30 pages for the Ebon Dragon, on top of 59 pages for the main document, and however many for the other Yozi, all for a different edition than where these mechanics started. I found 18 pages of charms for the same edition pretty tiring. I admire your work ethic.
Here's a link to my
Ebon Dragon Re-Write 2e.
For the excellency, how about only italicizing the word "dark" in "dark truths" but adding italics to "reveal the" so that "horrible truth" is an action rather than a static item?
For the Mythos Exultant, given the parallel to Adorjan's it seems like it should cost willpower proportionate to the stunt rating to resist, rather than scaling the number of targets. Might also want some cap on how many WP it can cost someone over the course of a scene, and consideration of range both spatial and temporal. For example, does the illusion linger in footprints to bamboozle someone following the infernal's tracks, or analyzing a crime scene?
If you're going to change the Imperfection (which I don't think is really necessary) it should be unambiguous. How about a 3m surcharge in any light bright enough to read by, unless you've got at least 50% cover relative to either the light source or the attacker, and the defense fails outright when fully exposed to true sunlight?
For Fate-Rending Desperation... Touch effects don't normally have range.
Ever-Hungry Shadow Infliction seems to be condensing the effects of five charm purchases (the Life-Denying Hate tree, apart from the upgrade to require sapphire circle countermagic) into four. Adds the Crippling keyword, but removes the ability to become immune for a scene by breaking the curse. Is a single use of the charm meant to apply as many of the effects as you know? It's ambiguous, and that would be a significant power boost if so. The names are clearly a reference to that old joke about the laws of thermodynamics, but the phrasing is a bit awkward. Here's my proposal:
Let's Play A Game: The target of this curse is displaced from their own metaphysical identity. Prayers and Infallible Messengers directed to whoever they were before the curse will arrive only after it ends. Anyone given the slightest cause for suspicion will view them as a proven impostor, despite the lack of physical changes. If they have a bane, such as rowan wood for the luminata or iron for rakshasa, the infernal intuitively understands what it is and can assign something else to fill that role for the duration - however, the new bane must be present in the scene or otherwise reasonably obtainable, at the ST's discretion. Likewise, any ongoing astrological modifiers are perfectly comprehended and temporarily subverted into comparable effects with a few crucial details changed.
You Can't Win: All the target's mote recovery is reduced by half, including from hearthstones and stunt awards. If something else is also impeding respiration, such as being a living essence user in a shadowland, stunts give full awards but any other mote recovery is impossible.
You Can't Break Even: The target cannot heal damage by any means, unless they're currently taking ongoing damage from e.g. poison, bleeding, or a hostile environment such as a bonfire, in which case they can be healed by effects that conceal injuries (such as the Snakeskin Stone) or convert damage to a less serious type, but still nothing that would restore perfect health.
You Can't Go Home: The target gains no benefit whatsoever from rest or sleep, and can only recover willpower through progress toward, or stunts resonating with, a Motivation they do not expect to survive. Any Motivation which could reasonably be concluded in an unqualified glorious triumph, or continued indefinitely, is ineligible.
A spirit killed while under the effects of any two (or more) of these curses is shunted into the darkness beyond existence unless it perishes exposed to sunlight. Within this oubliette of perfect solitude, the spirit experiences the passage of time and nothing else, forever. From time to time, the Infernal dreams of the exiled spirit's pain, but the exile is functionally annihilated from the perspective of Creation and ceases to be a valid target for effects... other than Void Circle Necromancy. This banishment is ineffective against entities that are already complete worlds unto themselves, such as the Yozis, and a Deathlord defeated in such a way would likely break free at the next Calibration if not sooner. Specialized sorcery might allow indirect interaction, best-known example of such being the Eyeless Face.
Despair-Choked Spirit Maiming definitely shouldn't include an option to make it not count as a charm activation, errata got rid of all those sort of effects for good reason. Also seems like it becomes way too easy to load someone with effects that require adamant countermagic to break - possible right at E4 with a Twice-Striking Lightning Prism. You've already cut out the possibility of mere scenelong curses entirely, does it really have to be an upgrade straight from days to indefinite? No intervening stops at months, seasons, year-and-a-day, centuries? No extra costs?
Proposed changes to Witness To Darkness are a transparent attempt to nerf the penalties, which I disagree with. I think it's really more of a problem with the larger system failing to clarify underlying assumptions about Manipulation and Charisma being Yin and Yang, so, not worth getting into that argument here.
Shared Boundary Divination seems like a speedbump, and it's unclear what making the action "undetectable" means. Might want to be careful not to step on Cecelyne's toes, when she's got Knowing The Desolate Heart => Inner Voice Betrayal. How about basing it more on Naked Wicked Souls from BWC, dropping those bland bonus successes (which Witness To Darkness already has), instead supplementing a Read Motivation action to negate penalties for physical concealment or language barriers, incidentally letting you eavesdrop on people right through the clamor of Hell or an almost-but-not-quite-perfectly soundproof wall, or play along in a conversation where you can't understand a single word sorta like receive-only versions of Poetic Expression Style + Excellent Emissary's Tongue?
I like the idea of Seeing Is Blindness being an upgrade to Life-Blighting Emptiness Attack rather than standing alone, and affecting other senses, but I don't like the mechanics. How about, if they take at least one health level of damage from the prerequisite, they have to make an opposed roll against themselves: Appearance + Integrity vs. Perception + Awareness. If the Integrity roll wins, they deny the ugly truth and in doing so lose access to one sense, attacker's choice from the usual list of [sight], [hearing & touch], [smell & taste], [misc./other], either for the rest of the scene, or, at E4+, indefinitely as a sorcerous derangement. If the Awareness roll wins, they've stared directly into the abyss and thereby negated any physical injury from the attack, including the mundane component, but are at a -1 internal penalty to Perception- and Wits-based dice pools and static values per health level they would otherwise have taken, which is about as difficult to heal as aggravated damage. If it's a tie they get to choose, but if either roll botches, they get both effects.
For Nemesis Self Imagined Anew, you know there's a simple canon way to get around the "living creatures" restriction, right? Wickedness Beyond Life and Cornered Titan Desperation are both deliberate thematic statements about the Ebon Dragon breaking even his own rules.
The downside to Heart Shrouding Opposition seems weak and tacked-on. I'd rather find some way to salvage the much more thematically rich charms building off of Brooding Resentment Defense in BWC, Victory In Defeat and Mocking Murmurs Retort.
First purchase of Impersonal Presence Declaration is way too weak, and mostly redundant with the excellency anyway. Turn it into a joke about Heisenberg's Uncertainty Principle, instead: the more they know about your momentum, the less they know about your position. In mechanical terms, any and all penalties or applicability problems impairing the infernal's Dodge DV are also applied to observers' Perception + Awareness pools when opposing the infernal's Dexterity + Stealth in combat.
Then make the upgrade a step 9 reflexive, allowing a faster-than-normal attempt to reestablish surprise. Maybe multiply threshold successes for damage purposes by the number of swings they took at you in that flurry before you slipped away, if you keep the motes committed and maintain stealth. Probably make the retaliation specific to ranged attacks, so Cornered Titan Desperation can apply to more than just Life-Blighting Emptiness Attack.
Sneaky Shadow Trick by itself is just a narrower version of Shadow Spite Curse with an area effect and a mote discount. I'd say go for the counter-forensics first, make it a perfect effect (against mundane scrutiny, at the very least - compare sidereal stuff like Avoidance Kata or the lunar wits charm The Spider's Trap Door), then have an upgrade to Shadow Spite Curse with Sneaky Shadow Trick as prerequisite: whenever Shadow Spite Curse is applied to penalize a reflexive action to notice something, or any attempt to
avoid noticing something (often but not always meaning Dodge MDV), you can add 1 wp and commit the motes to make it apply to every such action involving the same subject by anyone within range for the rest of the scene.
...and you've got Bloodless Murk Evasion as 4m instead of 8m.
That identity-loss curse for Ever-Hungry Shadow Infliction would make a good additional prerequisite for the shintai.