A new combat mage spell

[Elder-Basilisk]

What would you think of the following spell:

Greater Enlarge:
Transmutation
Level: Sor/Wiz 4
Components: V,S
Casting time: 1 action
Range: Personal
Duration: 10 minutes/level

This spell transforms the caster's body into a larger and tougher version of his natural form. The caster gains a +6 bonus to strength and +6 natural armor, and becomes one size larger with the normal -1 size penalty to attack and armor class for size increases and the normal increase in reach for the size. In addition, the character's equipment grows as well and the damage die of any weapons wielded by the caster increases by one step along the following table (in order to account for the increase in size):

d4--d6
d6--d8
d8--d10
d10--2d6
2d6--2d8
2d8--2d10

It's clearly superior to Righteous Might but it's true comparitive target would be Polymorph Self. If polymorph self were really a balanced 4th level spell, this spell (which is clearly inferior at 1/6 the duration, and a generally inferior stat increase compared to the typical troll, hill/stone/fire giant, Annis, Green Hag forms for increasing combat potential and is obviously far far less versatile, covering only the combat boost aspects of Polymorph Self rather than the mobility, speed, stealth, disguise, etc aspects of the spell) would probably balanced at 3rd. But I don't think Polymorph Self is really a very balanced 4th level spell. . . .

 

[BiggusGeekus@Work]

I think this is OK given that the range is "personal". This would be NASTY if cast on a fighter with a halberd or something like that.