i.e. If you received 1000 xps for killing a big monster, alone you would
receive 1000 xps, with one friend only 500, 2 friends 333, 3 friend 250. With
the full 6 guys in a group, you'd only get 167 xps.
Sometimes I'll take my main guy out to kill some creatures, come back for
healing, go out again, kill, etc.
-Rad