I agree LokiDR.
Here's one inspiration from Youspoonybard's idea, put at lvl 9 as a backup for a campaign I play in that finds itself outdoors a lot:
Daedra, male human Druid 9, Neutral
Animal Companion:
http://www.afunk.com/mammals/rhinocerous/pictures/001.jpg
HP 10d8+50, AC 18, Gore +14 for 2d6+12
Extra feat from Hd increase: Power Attack
Feats:
Mounted Combat
Combat Reflexes
Natural Spell
Spell Focus (Conjuration)
Augment Summoning
Daedra either trades out scimitar proficiency (at DM permission) for Longspear, or maybe buys it with a martial weapon prof.
Stats: High wis, High dex,
Typical tactic in favored terrains:
Scout out enemy in bird form.
Wild shape into Dire Ape form (+4 nat. armor, 10' reach, +6 Str Mod)
Cast Call Lightning or Lightning Storm for use when needed
Summon 1d4+1 dire wolves or tigers (or single rhinocerous)
Animal Growth himself, the rhino companion, and 2 other summoned animals
Daedra gains Huge Size, 15' reach, +10 STR mod, +36 HP
Rhino gains Huge Size, 10' reach
Daedra charges on his Rhino:
Rhino attacks at +17 for 6d6+32
Daedra attacks with Longspear
Combat reflexes lets him hurt those that provoke AOO's while casting spells each round or dropping lightning bolts, while his mount moves him around the field, charging foes for 6d6+32 each time. Meanwhile his summoned dire wolves (with +4 STR and CON from augment summoning and +8 Str from animal growth) harrass, trip and grapple his foes.