Format:
groupcast <spell>
groupcast <spell> group
groupcast <spell> <target>

The groupcasting skill allows several clerics to form a casting circle to cast
a spell at a higher level.  The leader of the circle must be able to cast the
spell, and only clerical spells lend themselves easily to casting in this
fashion.  By this same token, circle members must not be fighting.

When a spell is successfuly cast, mana is taken from all group members in as
even a fashion as possible.

There are two different targeting methods.  The first is to concentrate the
focus of the group onto a single target.  The second casts the spell on every
member of the group.

Since the casting circle is based on clerical paradigms, the 'heal' spell is
much more powerful when cast.  A single target can be healed completely in a
single cast, and a group can use all available mana to heal the entirety of
the group should need arise.