Magic Siege Engine, Greater

Transmutation
Level: Antipaladin* 4, Artificer * 4, Cleric */Oracle * 5, Inquisitor * 4, Paladin * 4, Sorcerer */Wizard * 4
Components: V, S, M/DF (black powder)
Casting Time: 1 Standard Action
Range: close (25 ft. + 5 ft./2 levels)
Target: one siege engine touched
Duration: 1 hour/level
Saving Throw: Will negates (harmless, object)
Spell Resistance: yes (harmless, object)
  This spell functions like magic siege weapon, except it gives an indirect fire siege weapon an Enhancement Bonus on targeting and damage rolls of +1 per four Caster Levels (maximum +5). If used on a direct-fire siege weapon, this spell functions as greater magic weapon.