Shade said:
I could go either way on its fatality. Since the slaad implant kills 'em, I just modeled it the same. Regardless, it should at least do a fair amount of damage on its way out.
well, if we’re going to have this as an ability at all, we might as well make it fatal.

and, innovating on an already existing creature might make it even more attractive for printing.

note that on the original, the chrysalis hatches in 1d6 hours, not a week, thus a short ship journey would be enough to kill someone.
Shade said:
For the object, rather than destroying it, should it instead do hp damage? This way, a ship wouldn't be destroyed but a crate might. If so, maybe 3d6 damage per hour (which bypasses hardness)?
that seems reasonable. I mean, the larva is forming itself from the materials around it – so, while that would completely destroy smaller objects, a bigger object like a ship would just need to be repaired. And I like the addition of corporeal undead and constructs, which would be treated as objects for the purposes of this attack. Don’t forget that part of their bodies consist of whatever material the spores used to form the chrysalis.
Given that we are turning the voor dust into an ability, the flavor text needs to be rewritten, so let’s try this:
The murderous voor were once the ancient racial enemies of the illithids. The two races warred for centuries, until the illithids began to win, and the voor retreated to the Astral plane. Eventually, the illithids found the last of them and managed to annihilate all the living voor. No record of their existence remains.
Before they were destroyed, the voor formed huge clouds of mist on the Astral plane to store their dormant seed. Githyanki and other creatures of the Astral know to avoid these greenish clouds. This ancient mist stores voor dust, which can infest anything that moves through it. This instrument of the voors’ vengeance will attach spores to any creature or object, which will grow into new larvae. Since the elimination of the voor so many centuries ago, no known voor larva has yet reached the adult stage.
A voor larva is 8 feet long, and weighs X pounds.
Combat
A voor larva’s wings don’t allow the creature to fly, but their tips are razor sharp and are used as claws instead. Usually, a single larva will produce a trill while the others in its group press the attack. Hatred of illithids remains in the voor’s racial memory, and larvae will try to destroy any they find. Newly hatched voor larvae will search meticulously for life forms before securing that area and moving on. Larvae will destroy any organic creatures on the chance that they may be mind flayer thralls.