Considering we are all good mannered players and we play for fun, I think we could perhaps use simple rules like this. Let me know what do you think. Simplicity with important points.
General PvP rules
1. Mana potions are allowed for all classes (except for the ES sorceress).
2. It is allowed to drop potions in front of blood moor entrance. Same applies to arrows.
3. No merc
Skills
4. Banned skills are: Slow Missiles, Holy Freeze, Meditation, Prayer, Cleansing, Iron Maiden, Decrepify, Bone Prison, Life Tap and Clay Golem. Those skills are banned in any form or shape, regardless of their source. (Doom, Exile, Lawbringer etc)
5. Items containing banned skills charges aren't banned but using those charges is. (Marrowwalks, Sanctuary etc)
6. Cold Mastery is capped at one point only for Blizzard sorceress class. - questionable if we duel on Nightmare
Absorb
7. Maximum resists are capped at 85 without any absorb.
8. 75 resists + 20% absorb is allowed, 80 resists + 12% sorb is allowed.
9. Banned items: 1.07 LoH, Rising Sun, Blackoak Shield, Hotspurs, Thundergods Vigor.
Prebuff
10. You could ask other players if it is okay to prebuff, but generally no one does that except specific builds