Partying, right now, is rarely done. A large part of that is lack of players, of course. But even when we had players it was seldom done because it's DECREASES your xp gain, due to the division of xp. Higher level players have no mechanical motivation to party with lower level characters. Most interaction is people teleporting to others, casting shields / planars, then teleporting away.

Occasionally people do form up to combat very challenging opponents (Tulu, dragons), but for the farming/grinding that is a large majority of playtime partying is actually a penalty.

I believe changing this would increase interaction between players, which would be a good thing (tm).

SIMPLE CHANGES:
  Make party xp much better. REWARD players with an xp bonus for forming groups.
    Something like: Your Exp = Total Normal XP * Your Level / Highest Party Member's Level
    So someone 50 levels under isn't getting /hilarious/ xp, but highbie isn't outright punished for letting someone tag along.

 * Remove Party level limits:
    We have a huge friggin' range of levels in people playing. If there's some mostly-fair-enough xp gain ratio, then there shouldn't be a problem with high mortals following reno/max around.

 * Make area spells not hit party members:
     Casters in parties want to use area spells, because... they're good against masses of units you might fight as a party? But they can't, because oh no now Mike is on fire / the dwarven merchant is covered in lava.


NOT AT ALL SIMPLE CHANGES:
  A lot of muds have some sort of formation system. Where you can stick around the back row and be safe from hits, stick in the front and opponents have to hit you.
  We do have guard, but it's... weird and awkward. It works fine for two people, more than that and you have to form some weird, easily disrupted daisy chain of guards.

Here's a general idea for a simple system:
"Stand in Front" Take the front row
"Stand in back" Take the back row (only works if someone is in front. You are defaulted to front when joining a party)
One handed weapons reach from front row to anyone in an opposing front row. Two-handed weapons (roughly equal to greatswords, bows, polearms, et al) reach from back to front or front to back.

Spells target as normal (could be changed, but would be... something to do after a lot of other work, above.)

Combat actions could be altered fairly easy to have realistic restrictions (no headbutting someone with two intervening shieldwalls)

-Mahk
