Mostly I am looking at Negative Energy pg 60
Particularly when combined with Selective Channeling pg 51 and to some degree Extra Turning pg 50.
This is a real combo bomb here; especially at low levels.
Negative Energy does 1d6 damage to all living creatures in 30' radius with DC 10 +1/2 lvl +Cha bonus.
Clerical Turns per day are 3+Cha bonus.
Take a Cha 16 cleric that takes the feat Selective Channeling.
The cleric can AoE in a 30' radius doing 1d6 for half against Will Save of DC 13 up to 6 times in a row or spread over that many attacks. That is good damage and awesome blasting for a level 1 cleric without even touching their spell list.
I can not tell you how the wizards and sorcerers would be jealous of that kind of ability. You do not even need to be evil but a neutral faith will still allow you the damage (though many clerics might want to turn evil for damage out put like this).
The damage effect also scales and can be made to affect Outsiders and Elementals thanks to Turn Elemental and Turn Outsider on pg 52.
By level 10, the Cleric that increased their Cha to 18 and took the Extra Turning feat once (though this is likely a feat that could be taken multiple times with each selection adding another 2 usages).
The 10th level Cleric now can AoE in a 30' doing 1d6+4d6= 5d6 damage with Will save DC 10+5+4= 19 for a total of 3+4+2= 9 times per day and could be affecing Elementals or Outsiders beside Living targets.
You might argue that Fireball can do more damage by 10th level but this is pretty free spell choices for damage, the AoE at 30' radius is larger then most Fireballs and then their is Selective Channeling.
Selective Channeling is the real game breaker. Taking this feat means that you do not blast your friends with all this damage that the cleric is doing without even opening their prayer book.
You automatically get the ability to exclude your own self from the negative damage as part of Negative Channeling. Selective Channeling lets you protect up to your Cha bonus in other targets. Given the very average 16 Cha Cleric then this gives three people (usually enough to exclude any of the other members within 30' of the Cleric).
A Cleric dedicated to this combo would start with a higher Cha and a race like Gnome which is +2 on Cha and thus possibly a Cha 20 starting race at level 1.
A Cleric of this type would focus almost strictly on being able to spam this power while using their spells to protect them as they just walked around killing things with their field of death.
Worst case situation by level 20 using a Gnome base with 18 Cha before racial modifer and taking multiple Extra Turnings.
Cha would be 25 with bonus +7. Feats would be Selective Turning, Turn Elementals, Turn Outsiders, Extra Turning x7 (+14 bonus turnings per day).
The Cleric can now AoE for 30' radius doing 1d6+9d6= 10d6 damage with Will Save for half of 10+10+7= 27 for a total of 3+7+14= 24 times per day affecting both Elementals and Outsiders (also any undead are just extra recruits for the front line for this character).
They really do not need their spell list as they have plenty of combat power already and just spam channelings all the time.
A good summary of all the issues with Energy Channeling in one place, but this thread really should be in the Magic and Spells threads.
Positive Energy Clerics should be engaged in melee; Negative clerics in melee. Opposing clerics of different energy types cancel.
At level 1, the wizards only damage one target, but they can do it all day long. (The fighter vs fireball argument.)
At level 3+, it does get slightly unbalanced. I'd recommend resolving this issue with an energy pool. One point equals 1d6 energy release. The trick is finding a balance that works. This also has the advantage for positive energy channelers of being able to release 1d6 healing multiple times for an area stabilize effect.
I might raise the range of the wizard's at will blasts to 60, but would check other issues first. Namely, 30 feet is within sneak attack range and PB shot, while sixty feet isn't. Hm, maybe add rogue training for sneak attack within first range increment, but that has its own balancing issues.
Anyway, real life just interfered. My main point is some of these issues have been brought up in other threads.