Kit:
Void Claimed template is looking damm snazzy
I think I would be interesting in including it, with your permission of course. Its original, as I havent seen any similar template so far.
Blacksad:
hope that it doesn't border too much with summoning
Not at all, I was thinking of various things, amongst those forcing down demons & devils to inhabit the bodies of the dead. Also, I am working on introducing spirits (in the way they are represented in such mythologies as the American-Indian and Greek/Roman ones).
Have you seen the Mechanithrall in the Monsternomicon from Privateer Press? It would be cool to have rules to create such a creature (there is already rules to create undead thrall in the book plus a bit in the errata, but the mechanithrall miss such rules).
I have seen it in fact. Im making the Mechanical Grafts aside from the creatures, so that the DM will be able of building his own undeads instead of having a few selected creatures to choose from. I posted some examples on the Mechanical Grafts some time back.
An armor that grant undead immunities.
An amulet that make mindless undead to consider you like one of their own.
A weapon that graft itself to your hand/arm (a psionic spell can do this), and allow an undead to use its level drain / cold damage abilities through it (undead can't normaly do this).
There was actually a suggestion made further down that you could make weapons that simulate special abilities of some of the undeads, an Armor which grants special qualities would be a reasonable extension of this idea.
The amulet, isn't it simply like the spell "Invisibility to Undead"?
I think there actually was a spell in the Undead book that had that ability, cant remember if it was an amulet. You could eventually combine it with an armor granting undead immunities, making it an armor that also makes skeletons & zombies percieve you as one of such.
If you havent read the Vampire Template I posted earlier, it actually had Vampires that could use some of their special abilities through weapons. Vampires have difficulty using magical weapons, but they can sometimes transmit their own powers into the weapons they wield.
Something really evil, and that player won't expect, a template that make the attack of an undead linked to an element (acid), grant immunity to all other (sonic, fire, electricity, cold) and weakness to acid
Thats actually a cruel idea, having a creature that has an acid attack have weakness to acid (something that the players most definitely wont see comming). Like having a water elemental with cold vulnerability. Yet, there would have to be a "relatively" logical reason why the undead would have such an odd combination of abilities / immunities.
Secret College of Necromancy had a funny spell that recalled a spirit in a skull, and it was possible to do it on a skeleton, and to allow it to control its body. My idea would be to grant ECL to the mindless undead, just in case someone grant them intelligence, it could fun.
I saw some amusing spells at Realms of Evil too, a series of spells that would allow a Necromancer to create a zombie that had the same ability score as him in one of his ability scores. The advanced would even allow the zombie to have to of its casters scores (like intelligence & wisdom). Actually gave me a good idea for an amusing adventure. The players are attacked by a lone zombie. The day after the slay it, they suddenly see several zombies standing around the corpse of the first zombie. Dressed in trenchcoats, wielding magnifying glasses and smoking big detective-pipes, the newly arrived zombies are trying to discover the cause of death for their former friend.
A player of mine (Necromancer/Druid, sounds unlikely, but he wanted to play it soo...) once created a spell for creating Zombie Gardeners.
Something that I found strange in the first PDF was that it was really hard to build a permanent undead army, so perhaps including the legion spells from the secret college of necromancy would be good?
I finished my proposal for a new Necromancer Base Class a few days ago. One of the things I gave them was an increased ability to command undeads, since it would help explain why a Necromancer could possibly create a large army (not only a small band of 10-15 zombies like a PhB wizard can). Many of the things I am working on are items specifically made for undead armies.
A spell that allow a vampire or liche to trade some or all of its immunity to become partially or totally human again for a time.
Not a bad idea. Perhaps the spell wouldn't have a big advantage for the undead, since it removes most of its abilities and immunities, but it could be interesting for role-playing purposes. It makes me think of the fourth book in Anne Rice's Vampire Chronicles, where Lestat goes to great lengths to "borrow" a human body from some Psionically endowed person. Not for any other reason than being allowed to taste food again (as well as doing some other... typical human things which I wont describe).