Globe of Fire
(Invocation/Evocation)

Range:  0
Components:  V, S, M
Duration:  1 round per level
Casting Time:  4
Area of Effect:  2-foot per level radius or less
Saving Throw:  Negates

Globe of fire is a wizard's last line of defense. When cast, a fireball goes off, centred on the wizard. However, the caster takes no damage from this fireball, and can act as if the fire did no exist (i.e., can see and hear normally). Any creature within 5 foot per level of the caster takes 1d6 damage per level of the caster.
Notice that the actual area of effect is left up to the caster, though the maximum size is 2 foot per level. Also, the spell lasts for a short while, protecting the wizard from physical attacks (i.e., swords, arrows, claws, etc., miss since the wizard is effectively shielded from view), spells (fire based spells add an extra round per damage die, cold base halves the duration, and all other spells are left up to the DM), breath weapons, and gaze attacks. The material component of this spell is a pinch of diamond dust, worth at least 400 gp.
As example, Jasper the mage is in way over his head. While travelling, he was beset by 20 bandits. So, he casts globe of fire to keep the attackers at bay. Since he is a 10th-level wizard, a globe of fire springs up that is 20 feet in diameter. Anyone caught in the area of effect takes 10d6 damage, taking half if saved.
However, note that Jasper's horse is probably dead.

