[Pre-BB] MapleStory Formula Compilation

In order to leech from a party member's kill you must
Be no more than 5 levels under the monster OR
Have done at least 1 HP in damage to the monster OR
Within 5 levels of any other party member that satisfies one of the first two conditions.

That one's wrong. If you have a hypothetical party at Jr. Newties (level 105) consisting of a 110, a 105, a 100, a 95, a 90, and an 85, the 85 will not get experience unless the 90 is the damage leader, or they hit the Newtie themselves.

I'm going to define a term I just made up:
Damage leader - the person in the party that dealt the most damage to a monster within their party.

Anyway, if the 95 is the damage leader on a monster and no one else attacks it, everyone will get a split based on their level except the 85. The 95 will get a bonus 20% for being the damage leader. If the 110 kills it, only the 110, 105, and 100 will receive experience. If the level 85 kills it solo, then everyone will share experience. Make sense?

According to your definition, if the 85 killed the Newtie, then the 95 would not receive experience. This is clearly not the case.

I'm going to say that the 3rd condition should actually be "Be no more than 5 levels below the damage leader on the monster."

In regards to killing misted monsters, my theory is that the reason finishing off a misted monster rewards 20% of the experience has to do with the qualities of Poison Myst itself, not the killing blow. If a monster is affected by Poison Myst , the damage it takes is attributed to the caster, but the damage dealt by poison does not count toward being the damage leader. When the random noob attacks the monster and hits for 1 damage, the game determines that the noob actually did more damage than the F/P and rewards them 20% of the monster's experience. The F/P then receives 80% of the remaining experience if they are on the map because they did 99.9% of the damage, which rounds to 100% of the remaining experience.

This can be tested in two ways: Explosion a monster and then poison it, and have someone kill it. If they receive 1 experience, then my theory is correct. If they still receive 20% experience, then it has to deal with the killing blow. Or, get a monster with a substantial amount of health (~10k+) to near 1 HP (might require careful planning) by some other means than poison (also try Sanctuary) and have someone kill it. Same process.

What I'm not certain of is when multiple parties attack a monster. If there is a party of 3 105s and a party of 3 110s, and the 110 party deals 40k damage to the Newtie, and the 105 party finishes it off, then how is experience determined?