Amulet of Resist Draining
Amulet of Resist Draining - rN+ and direct resistance to all forms of draining. (Sustain Abilities effect, AntiMagic melee and MP Drain Gaze (Ghost Moths and Eyes of Draining) take less MP, Vampires heal less from attacking you.)
I offer the idea because (1) SustAb is too good for a ring slot and should be bumped to amulet. (2) There is no way to resist MP Draining, which is annoying and often fatal. (3) Amulet of Warding is often referred to as the weakest amulet with the Warding effect almost never being helpful and the rN+ being its saving grace, and rN+ by itself really NOT being with an amulet slot. This combined item would be a fair choice of Amulet for anywhere with significant draining effects (Slime, Pan, Spider, Abyss etc.)