Which area you farm is decided by the area's monster level, not by the item —
the rule is the same for everything, so it lives on the
mechanics page.
NAMED TARGETS
Named monsters that can be farmed deliberately. The list spans all three difficulties;
each monster appears once, at its most rewarding one.
The figure is an estimated average kill count.
Duriel
normal · Lv 22~1 every 502 kills
Diablo
normal · Lv 40~1 every 2,008 kills
Hephasto The Armorer
normal · Lv 25~1 every 2,040 kills
Nihlathak
normal · Lv 65~1 every 3,604 kills
Mephisto
nightmare · Lv 59~1 every 3,646 kills
Baal
nightmare · Lv 75~1 every 3,921 kills
BASE ITEM DROPS
expected per kill
This counts how often the plain Ring drops. A dropped base still passes
a quality roll before becoming this item.