[Taqwus]

One might also argue Vastnesses, but it's somewhat dangerous.
+: lets you take advantage of incredible mobility
+: astral-3 lets you buff a bit (luck, at least)
-: astral-3; weak enough to be dueled, and it's not like R'lyeh is short of astral mages
-: cost; R'lyeh may not be rolling in nature gems


For earlier fun, a Living Statue has some value; it gets all slots, and has a niftily high basic protection.