Olympia: The Age of Gods PBEM (Oct 4 2000)
Combat spells cannot be cast until the second round of combat. There are two reasons for this rule.
First, this rule permits non-magical forces to capture a magician by overwhelming him before he can bring his potent magics to bear.
Second, this rules prevents attackers from draining a magician of his aura by sending a series of easily-defeated "nuisance" attacks against him.