New Role: Life Siphoner

[Turbonerd]

Name: Life Siphoner (could use re-working, maybe Vampire)
Description: You murder others in order to empower yourself.
Alignment: Neutral Evil, Neutral Killing
Abilities:
At night, the Life Siphoner kills someone.
If the kill is successful, the Life Siphoner gains an immunity, meaning the Life Siphoner can't be killed at night until all immunities are gone. So, if a Life Siphoner gets two successful attacks and has not been attacked, he has two nights of immunity. When attacked, he loses an immunity. They stack, and it's passive (meaning a night does not need to be wasted in order to use night immunity; they activate automatically).
The immunity is resistant to Veteran and Arsonist attacks. I'm not certain about Jailor: Maybe he would execute and kill the Life Siphoner, or maybe the Jailor just gets killed by the Life Siphoner if he jails the Life Siphoner.
The Life Siphoner only kills every other night (Default: ON).

In case this is too overpowered, here's a debuff: If he doesn't get a single kill in four nights, the Life Siphoner dies.

This is kind of rushed, so I might be missing things or things are unclear. Tell me if I am so I can correct them or make them more clear. Any suggestions and advice are acceptable so that my future suggestions aren't bad.

[Beuzmoker]

Is he immune to veteran, jailor, arsonist attacks ? because else it's just a nerfed SK.

[Reemus]

Can we just make a random appearing role that douses+role-blocks+sanitizes+gives false information when visited? Would be a lot nicer.

[Turbonerd]

Edited for clarity. Immunity is resistant to Arsonist burning and Veteran killing.

I'm not certain about the Jailor's case. He could just live through the execution, but that would out him. He could kill the Jailor, like Serial Killer, in a way. Or, of course, the Jailor can successfully execute the Life Siphoner.

[Cryptonic]

I'd say just have him survive the Jailor execute. Just count Jailor attack as a -1 to his shield.
If it takes a Jailor execution + lynch to kill him, then that's already incredibly powerful. No need to make him kill the Jailor.