What would happen to a Illumian in a Dead Magic Zone

[Barbarian Horde]

In some areas of Toril, the Weave is so warped or frayed that magic does not function reliably. This damage may be due to some magical disaster, such as those that were common during the Time of Troubles in 1358 DR. or due to some powerful effect that distorts the Weave, such as a mythal (see mythal). Most zones of wild magic created during the Time of Troubles have since disappeared, but small pockets of wild magic remain, especially underground and in wilderness areas.

In some areas of Toril, the Weave is absent altogether. The Weave has a tear or hole, and the area effectively has no magic at all. Like the rare wild magic zones, many regions of dead magic were created during the Time of Troubles and have since faded or retreated. Dead magic zones often persist in places where extreme concentrations of magical power were abruptly scattered or destroyed - in the vicinity of a shattered mythal, at the spot where an artifact was broken, or at the scene of a god's death.
So let us imagine one of these unfortunate sub human race walk into a dead magic zone. What would you say to your PC.

The illumians are a race created by sorcery. Through painstaking ritual, they have developed a mystical connection to the magic runes that make up their own alphabet. Glowing sigils surround them, granting the power of an eldritch language made flesh.

So if an area is void of magic, whats to sustain the magic in the form of flesh?

[Mr Adventurer]

It doesn't need to be sustained, it's made flesh. That's kind of the point.

[Inevitability]

'Magic made flesh' is kind of your answer already. The only beings that explicitly disappear inside a dead magic zone are incorporeal undead. Anything else; be it corporeal undead, constructs, magical beasts or even living spells, can move through one with its only issue being its temporarily lost supernatural abilities.

[Necroticplague]

So if an area is void of magic, whats to sustain the magic in the form of flesh?

The fact it's been made flesh. Flesh isn't effected by holes in the weave. Even creatures that are sustained more directly by magic aren't effected by holes in the weave (i.e, skeletons don't suddenly de-animate, golems aren't suddenly rendered inert piles of material).

[Barbarian Horde]

See I thought about that too. Then the other bit about the reason their flesh was created was through runes that form sigils that surround them that form said flesh. I had assumed that the runes them-self were connected to the weave via the ritual.

[Inevitability]

See I thought about that too. Then the other bit about the reason their flesh was created was through runes that form sigils that surround them that form said flesh. I had assumed that the runes them-self were connected to the weave via the ritual.

I'm pretty sure they are, in a sense. It's just that removing that connection doesn't kill the illumian, it just suppresses its supernatural abilities.

[Doc_Maynot]

Actually, with their Shadow fluff, they'd probably be more connected to the Shadow Weave than the normal one.

But yeah, their Su abilities would be suppressed. So they'd lose the major draw of the race, the Sigils and the benefits of them.