Party types to avoid
Some parties were never meant to work together. As Game Master, it's a good
idea to know what types of characters are incompatible with each other.
Parties like this always have fundamental weaknesses. For example, a party made
up of just fighter types would be fairly powerless against spirit entities,
demonic manifestations, and Undead. A party made up of missile-heavies would be
sorely lacking in hand-to-hand combat. Likewise, a party composed of just
Priests would be vulnerable in most "Dungeon" settings.
Certain character classes get along quite poorly. For example, a Gunslinger
(being highly Lawful) would have no love for a Shaman (almost always Chaotic.)
In fact, their powers sometimes interfere with each other. Likewise, a Paladin
(being of Holy alignment) would have a tendency to lord over a thiefly type.
Finally, do not -- ever -- allow a player character to play a Scaxathrom Priest,
a Crystallin, or an adherent to an evil religion. For those other members who
worship the True One, the presence of summoners and witches would be
incompatible.