Harrim is a mess. He might not seem like a troubled character early on (aside from his obvious mental/religious disturbance), mostly due to his affinity for heavy armor and decent (for a Cleric) Strength score, but it won’t be long before more sophisticated builds are vastly exceeding his Armor Class, and unfortunately for Harrim, durability does not make a tank in Pathfinder: Kingmaker - not taking the hits in the first place is what you need to do. Likewise his lack of melee competence will quickly be exposed as well, although the flaws of rival companions like Amiri and Jaethal allow Harrim more cover than he honestly should have.

Instead of trying to cobble together a complicated build and tossing good equipment at Harrim to make him a mediocre off-tank (something that’s possible, yet of dubious utility) we decide to abandon the things Harrim’s not good at, give up any pretenses of being a front-liner, and focus on what he can do well. He’s got an 18 Wisdom and access to the Destruction Domain, which will net him spells like Disintegrate, Horrid Wilting and Tsunami. He can be a downright fearsome blaster-caster if we make the attempt.

Of course, Cleric spells aren’t the best, and if you just needed a dedicated healer, why not use Tristian? In fact, there’s not much of a compelling reason to keep most any Cleric as a single-classed character. The solution is simple and dare we say, obvious; a Sorcerer (Empyreal Sorcerer) will use the character’s Wisdom to determine spell potency, and when you qualify for Mystic Theurge at 8th-level you can begin progressing as both a Cleric and Sorcerer simultaneously. The downsides, of course, are that you’ll need to waste several levels on Cleric/Sorcerer, during which you obviously will only be progressing in one of your two spellcasting classes. Compared to a single-class caster, you’ll be behind by perhaps one or two spellcasting levels, which is a huge deal - perhaps crippling for a primary spellcaster - but the end result may well be worth the downsides.

Levels 2-3: Cleric Levels¶

Harrim starts out with one level as a generic Cleric. Get him up to 3rd-level as a Cleric and split his Skill Points between Knowledge (Arcana) and Lore (Religion). Both of these need to be at least rank 3, and you’ll probably want to end up maxing one. Focus him in Necromancy, as he’ll acquire spells like Glitterdust, Stinking Cloud, Slow and Obsidian Flow far too late to be worth specializing in either Conjuration or Transmutation, and his Dexterity really precludes him from attempting to use Ray attacks like Disintegrate the way, say, Octavia can. He’ll eventually end up with Boneshaker, which will deal decent damage, especially if you target foes with lower Fortitude Saves, like enemy casters.

Levels 4-7: Sorcerer Levels¶

Once Harrim hits 3rd-level as a Cleric, he’ll get 2nd-level divine spells, which is all he needs for that part of the requirement for Mystic Theurge. That being the case, it’s time to switch to Sorcerer, specifically the Empyreal Sorcerer subclass, which will use Harrim’s excellent Wisdom to determine magical proficiency.

Raise him up to a 4th-level Sorcerer, grabbing mostly general buffing and debuffing spells like Mage Armor, Grease, Reduce Person and finally Boneshaker, which is such a useful offensive tool that you might as well have it on both his Cleric and Sorcerer spell lists. Feats-wise Harrim will pick up Spell Specialization and focus on Boneshaker , then he’ll grab Spell Pentration.

Skills-wise, get both Knowledge (Arcana) and Lore (Religion) up to rank 3, then start dropping points into Perception until it’s maxed. At some point you’ll need to pick between Knowledge (Arcana) and Lore (Religion), as you’ll only get two skill points per level - enough to keep Perception maxed and one of the two aforementioned skills, but not both.

Levels 8-17: Mystic Theurge Levels¶

Harrim will spend the next ten levels as a Mystic Theurge, which will improve his spellcasting abilities as both a Cleric and a Sorcerer. At the beginning of this stretch you’ll want to grab Metamagic: Extend, as he’ll gain the spell levels to actually use it, and with two spell lists he can sacrifice some diversity in order to double the duration on some of his “one round/level” buffs, like Displacement, Haste and Prayer.

Also note that due to being a Mystic Theurge, Harrim can prepare a selection of Sorcerer spells using his Cleric spell slots, and he can also cast some of his Cleric spells spontaneously using his Sorcerer spell slots. Doing this forces you to use a higher level spell slot than normal, however; for example, casting Magic Missile as a Cleric would use up a 2nd-level Cleric spell slot. Definitely not a bad thing, and it heavily mitigates the need for Metamagic: Heighten Spell. Also, given Harrim’s slow progression (he’s only got 3rd-level Cleric/Sorcere4 spells by 10th-level), he’s really not a good choice for any Metamagic Rods you find. He’s also got more feats than he really needs, given the limited utility of stack Spell Focus on him, so he can just pick up Metamagic: Empower and Metamagic: Quicken as he levels up.