Level 5
Brother Chthonius, sadly, is a bit of a slow developer. However, by level 5 he's developed the level of ecclesiastical whack that allows him to keep the minions healthy and ready for battle, while at the same time keeping those pesky undead off his back long enough for him to do his job.
Brother Chthonius, male human Clr5: CR 5; Medium Humanoid (Human); HD 5d8; hp 26; Init -1 (Dex); Spd 15 ft. (armour, medium load); AC 18 (-1 Dex, +7 armour, +2 shield), touch 9, flat-footed 18; Base Atk +3; Grp +4; Atk +5 melee (1d8+1, masterwork heavy mace) or +2 ranged (1d4, sling); Full Atk +5 melee (1d8+1, masterwork heavy mace) or +2 ranged (1d4, sling); Space/Reach 5 ft./5 ft.; SA Turn undead; SQ Aura, cast divination spells at +1 caster level, good fortune 1/day, spontaneous casting; AL N; SV Fort +4, Ref +0, Will +7; Str 13, Dex 8, Con 10, Int 14, Wis 16, Cha 12.
Languages: Celestial, Common, Goblin.
Skills and Feats: Concentration +8, Heal +11, Knowledge (arcana, dungeoneering, nature, religion) +7, Knowledge (architecture and engineering) +3, Spellcraft +12, Survival +3 (+5 underground, +5 aboveground); Combat Casting, Extra Turning, Scribe Scroll.
Cleric Spells Prepared (5/5/4/3, base DC = 13 + spell level): 0-create water, guidance, light, read magic, detect magic; 1st-comprehend language, detect secret doors*, magic weapon, shield of faith, summon monster I; 2nd-detect thoughts*, find traps, make whole, owl's wisdom; 3rd-create food and water, protection from energy*, stone shape.
* Domain spell. Domains: Knowledge, Luck.
Possessions: Masterwork heavy mace, sling, 20 alchemical silver sling bullets, +1 banded mail, heavy wooden shield, 2 scrolls of bless water [5th-level caster], 4 scrolls of cure light wounds [5th-level caster], 2 scrolls of cure moderate wounds [5th-level caster], scroll of cure serious wounds [5th-level caster], 2 scrolls of owl's wisdom [5th-level caster], scroll of remove curse [5th-level caster], 2 scrolls of shield of faith [5th-level caster], silver holy symbol (25 gp), explorer?s outfit, backpack [cleric?s vestments, 50 ft. silk rope, 2 weeks? trail rations, waterskin], everburning torch, 2 healer?s kits, 2 flasks of holy water, 55 gp.
As before, skill synergies have come into play. This time it's his Knowledge skills that grant all those bonuses. Knowledge (dungeoneering) gives him a bonus to Survival checks when underground, while Knowledge (religion) has given Cthonius another slight edge when turning undead. Knowledge (arcana) bumps the Spellcraft up a bit. For now, we're going to exploit the facts that Brother Chthonius can pick up any Knowledge skills as class skills, and that Knowledge grants a lot of synergies by putting 5 ranks into as many Knowledge skills as possible; he'll be a little knowledgeable about everything. As you can see, he's just started advancing Knowledge (nature) with an eye on getting another bonus on Survival checks.
Which feat? Tough choice. I figured Brother Chthonius would need to be well-equipped -- especially if he's going to really start treating the dungeon as his monastery. To that end I gave him Scribe Scroll to defray the cost of all of those scrolls. Furthermore, scrolls are tradeable and make useful gifts, bribes and rewards. If he wanted the adventurers to remove a particularly troublesome hobgoblin chieftain that has prevented him from surveying a network of caves, at least he can offer the PCs a suitable reward for their endeavours.