Blood Rage

Enchantment (Compulsion) [mind-affecting]
Level: Artificer * 3, Bard * 2, Cleric */Oracle * 3, Sorcerer */Wizard * 3
Components: V, S, M (a drop of blood from each creature to be affected)
Casting Time: 1 Standard Action
Range: close (25 ft. + 5 ft./2 levels)
Target: one willing living creature per 2 levels, no two of which may be more than 30 ft. apart
Duration: 1 round/level
Saving Throw: Will negates (harmless)
Spell Resistance: yes (harmless)
  The targets of this spell become angrier as they fight, the pain of their wounds fueling their Strength. An affected creature gains a cumulative +2 Morale Bonus to Strength and a cumulative -1 penalty to AC for every 5 points of damage it takes (maximum +10 Strength, -5 AC) for the duration of the spell. These bonuses last until the spell expires or the target falls Unconscious.