I'm thinking maybe cleric casting, then, but probably bump to higher level (18-20?). Another alternative is to give him a boatload of SLAs, like what we did with the sea titan.
Awe (Su): Once per day (?), the Black Leopard may create an aura that can deeply affect mortals. All creatures that can see the Black Leopard must succeed on a DC X Will save to avoid the effects. A creature that succeeds on its saving throw remains immune to that t’uen-rin's awe for 24 hours. This effect lasts for 2d6+6 rounds (?). This is a mind-affecting effect. The save DC is Charisma-based.
The Black Leopard can choose from the following effects each round as a free action while its awe power is in effect:
Fascinate: Affected beings of 4HD or less stare at the Black Leopard in fascination. Awed creatures may defend themselves normally, but can take no other actions. Creatures of more than 4HD are instead dazzled.
Fright: Affected beings become shaken and suffer a –2 morale penalty on attack rolls, saves, and checks. The merest glance or gesture from the Black Leopard makes them frightened, and they flee as quickly as they can, although they can choose the path of their flight.
Resolve: The Black Leopard’s allies receive a +4 morale bonus on attack rolls, saves, and checks, while the Black Leopard’s foes receive a –4 morale penalty on attack rolls, saves, and checks.
How's that look?