Picking 3rd lvl medium spell

[Jinotad]

Hello, my reanimated medium just hit level 10, so I get to learn a single 3rd level spell.

I am a support medium, almost exclusively in the martial form. I spend every standard action giving everyone who can see and hear me +4 to all attack and damage rolls, or +4 to saving throws.

I have a quickened metamagic rod, so I can cast the spell as a swift action if need be.

Next level, it will only be a move action, rather than a standard to give the bonuses.

Since I am a very slow spell progression, I don't think offensive spells to be worthwhile as cast them as a lower level spell. (The plus to this, is they are lower for my metamagic rod.)

I was looking at taking greater invisibility, but was wondering if others would have a better recomendation.

[Firebug]

I find it is always useful to have a Dispel Magic or Fly just in case.
Possession is a remarkably low discount at 3 for Medium... and you'll likely be able to do all of your tactics as normal while utilizing it.