Help me finish this build (pf)

[Stormageddon]

Evangelist cleric 1/cavalier 4/battle herald 10. Need advice on how to finish this character. I want him to be an excellent buffer with the need of spells.

[avr]

Based on the levels chosen so far I guess you mean without the need of spells?

Chevalier (http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/c-d/chevalier) 1 gets aura of courage. The other 2 levels of the PrC affect yourself rather than others but might still be useful and/or appropriate.

Steel Falcon (http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/s-z/steel-falcon) gets some buffs but may not be terribly useful for levels 16-20.

A few levels of the Inquisitor base class might be of use. Not so much for the spellcasting, more for the other benefits.

[Person_Man]

Honestly, there isn't a strong finish to any of the theurge prestige classes. And the PrC in Pathfinder are generally weaker then the base classes. So I would only suggest using Battle Herald if you're going to be playing in a mid level game.

Also, I assume you know about the Horse Master feat, which keeps your Cavlier Mount scaled to your HD.