Smart Aim [General]
Benefit: When using a special attack which affects one or more targets, you may choose to delay its effects on some of these targets until the start of your next turn. If, at that time, those targets would no longer be valid (eg. they're out of range) they are unaffected. You may delay these effects even for a target you cannot see, as long as you are able to communicate a warning to them in some manner (such as a shout or gesture).
For example, if his teammates are engaged in melee with a group of orcs, a wizard could cast fireball while delaying its effects on his allies. The fireball affects the orcs immediately, but his teammates can avoid its effects if they move out of the blast radius within 1 round.
Don't tell me that giving this out for free couldn't help with certain types of problem player. Oh, and you can also take enemies by surprise by smart aiming Silent spells or something. Or go around telling people they're already dead.