The best protective spells are in... Necromancy? I'm I missing a rule?

[JAlexWarr]

System: Pathfinder, level 10.

While researching a big bad guy, I came across the idea of a Necromancer who sincerely believes that saving people's souls from being absorbed on death by the various deities to power their own inscrutable political moves is morally and ethically the Right thing to do. He believes that turning people into sentient undead can anchor souls to the Material and save them from the ravages of the outer planes. In his mind, "Evil" is the right thing to be because "Good" is defined by a system designed to exploit mortals.

Anyway, he's into Necromancy and really, really obsessed with avoiding death. But he isn't powerful enough to transform himself into lich, etc.

He is using a combination of Astral Projection, Lesser + Magic Jar + Skinsend + Shadow Projection to give himself multiple layers of protections against death. Basically his astral form rematerializes on the Material, he grabs a random commoner with Magic Jar, sends that commoners' skin out, and Shadow Projects from the skin.

He then ambushes the Players' party in shadow form, using Silent+Still metamagic to cast while in shadow form. So far he is an occasional harassment as the players work to find and storm the dungeon where his true body is held.

If the Shadow Form is damaged, he retreats to the Skin. If the Skin is destroyed, the commoner dies and the Necromancer is kicked back into his Astral Body. If that should, somehow, be killed, he is kicked back to his original body with -2 levels as a worst case scenario.

Studying the rules in play, this seems legal and very powerful. The players enjoy the challenge. But I'm worried I'm missing something that would invalidate this combination?

[Inevitability]

Scrying could probably lead to the players finding his 'true' body. Other than that, I can't really think of something.

[noob]

Do not forget protection against death which is the spell who gives the most needed immunity to adventurers.
it is also a necromancy spell.
In fact necromancy is a school where everything about death is which makes it a large spectrum school (due to that the Dread necromancer is not bad in 3.5) but in pathfinder I think skin-send is one too much layer of protection because it is too much low level compared to its power.(do not forget that your necromancer combo will make it have on average 2-4 HP because magic Jar gives you the hp of the target)