SRD you can trash any army or castle.
Cones are were its at. Greater Invis and flying above cones own fireball for area.
*Cone of cold basic is 60ft diameter.
*Shout 30ft.
*Chain Lightining is made of awesome.
*Rock to Mud.
*Wall of Fire (so people cannot escape from fogs)
*Shrink Item on boulders and trees and mass fly so the warriors can join in raining bouldery/tree death on the army from on high
*Major Creation (adamantium anvils are fun to drop on anything really.. i prefer farm houses but necessity .. something something something)
*Fabricate for war machines (need craft ranks... cleric can do this with miracle to fabricate and the complete adventurer spell divine insight or some such to get level to one skill check)
*Pyrotechnics (2nd level and 120 ft radius !!!!) blind a unit before a charge, bling archers as their unit lights their arrows etc
*Nightmare spell on their lesser generals/unit captains each night
*Permanent Image
*Polymorph Other (commoners fight better as war trolls)
*Wall of Iron (in the middle of ranks = either way it falls is a win)
*Planar Binding + Greater Invis (something with flight that has at will area attacks.. most demons do)
*Summon Monster as above.. choose things with range area spells or area fear effects
*Teleport Object (oil, greek fire, acid vats, caltrop sacks, BIG tanglefoot bags, your dms mom etc etc etc
*Unseen servant
*Telekinesis
*Reverse Gravity and Gust of Wind = use enemy as projectiles
*Etheral Jaunt
*Stone shape or crafts men making breakable globes with hinges or stuck together with wax... fire trap them all, put them in a sack, drop them... cluster bomb stylez
i'm spent