I've read a few guides and apparently Holy Arrow is useless? Other than that, heal can damage undead things, so do I train at undead monsters? I read Bella's bishop guide and she said go to brown teddies at 30, but those aren't undead so I'd be using magic claw, which would be way too slow. Is that what clerics do, or are there good undead spots all the way to 70?
Use magic claw until 35 with the teddies. After that, go to wraiths and hit them with heal until 40, you should be strong enough.
Chronos of all variety are terrible. Never go there. Go train at Wraiths at level 40 until 50/55 then move to Ghost Ship 2. Train at Ghost Ship 2 until 65 and head to Death Teddies.
I think grinding faster and getting to Genesis ASAP is time much more well spent than dealing with subpar money making and even more so XP rates.