Party

To party another player you have two options.

1. Type "/party playername" or
2. Go into peace mode, hold down ctrl and hold down left button on the player you wish to party until a portrait comes out.
Then proceed to drag the portrait into your party screen.

Party between different nations is allowed.

In your party screen you can see EXP, Weapon, and Spell at the top. This refers to what type of exp you wish to leech from other players. EXP will go towards your level, weapon will go towards weapon tactics, while spell will go towards spell tactics.

There is a level difference of 35 in order to leech EXP. Further, there is a spell and tactic cap that you can leech based on your level (It can only be a certain amount above your level). The maximum tactic level up until level 99 is 100. At level
100, you will become a crossing class and have the ability to raise your tactic level to 200. At crossing class there is a cap to your tactic level based on your level, the formula is: Level+20+(Level-100). Example if you are lvl 105 then your cap is
105+20+(105-100)=130.

Leeching cap table:

From the help built into the game client.