Not a handbook, but a full optimized lvl 20 build. Sole downside here is that the immortality comes at lvl 20.

Gaara of the Desert a.k.a. Mummra - the Everliving

The key ability here is from Walker in the Waste. The capstone ability turns you into an undead that returns when it gets killed somehow. You just need to place your organs into a safe place (explained in the build). Whatever happens, you will come back. There is no real way to prevent this. Even capturing and imprisonment doesn't help. He could just suicide and come back. You would need to put him into some kind of infinite stasis field that steals all actions to stop him.