This half-elf bard class ability strikes me as particularly strong:
Soothing Voice
A 1st-level bard with 3 or more ranks in Diplomacy can spend one daily use of his bardic music to use a composed, steady voice and reason to calm the emotions in others around him. This ability works in much the same way as the fascinate ability, with the following differences.
The creature to be soothed must be within 30 feet of the bard and must be able to understand the language he is speaking. To use this ability, the bard makes a Diplomacy check. His check result is the DC for each affected creature’s Will save against the effect. On a success, the creature is affected as if by the calm emotions spell.
The effect lasts as long as the creature listens to the bard, although the creature may wander off on its own if there is nothing to keep its interest.
Calm Emotions
This spell calms agitated creatures. You have no control over the affected creatures, but calm emotions can stop raging creatures from fighting or joyous ones from reveling. Creatures so affected cannot take violent actions (although they can defend themselves) or do anything destructive. Any aggressive action against or damage dealt to a calmed creature immediately breaks the spell on all calmed creatures.
This spell automatically suppresses (but does not dispel) any morale bonuses granted by spells such as bless, good hope, and rage, as well as negating a bard’s ability to inspire courage or a barbarian’s rage ability. It also suppresses any fear effects and removes the confused condition from all targets. While the spell lasts, a suppressed spell or effect has no effect. When the calm emotions spell ends, the original spell or effect takes hold of the creature again, provided that its duration has not expired in the meantime.
I don't think it's over-powered in the context of what a Wizard or Cleric can do, but it does seem very strong to me. It seems like it is very easy for a half-elf bard to avoid melee attacks virtually all the time. The DC is potentially very high (average of 20–30 at level 2), it's easy to activate a number of times per day, and the effect seems to turns off any melee-based opponents.
Are there limitations / strategies which make it less strong than it first appears?
Best Answer
The special ability soothing voice is a neat but limited trick
The 1st-level half-elf bard racial substitution level replaces countersong with soothing voice (Races of Destiny 157), which is like the bardic song fascinate but different, so below I've inserted soothing voice's differences into the description of the typical bard's fascinate special ability:
While the spell calm emotions is usually is a 2nd-level spell (therefore usually not available until at least character level 3 and higher than that for a bard), its usual range is medium, its usual area is a 20-ft.-radius spread, and its usual duration is concentration (up to 1 round/level). Although the special ability soothing voice's save DC will be higher than the spell—based as it is on a Diplomacy skill check—, a low-level character being able to use a few times per day this special ability (that draws its uses from the same pool as inspire courage, by the way) isn't overpowered, especially considering that the bard must have languages sufficient to be able to make himself understood to the creature (unlike the song fascinate) and that affected creature can just walk away if the bard's uninteresting (which is insulting and hilarious).
At higher levels, soothing voice is probably a waste of the bard's time, with him having much better things to do with his bardic music ability and him having spells that will do what he was trying to do with soothing voice better than soothing voice, but soothing voice may yet even then give the bard the opportunity to use his real Diplomacy skill, a skill that can wreck the game in the wrong hands. That is, at least, until higher levels in which the vast majority of creatures are immune to mind-affecting effects (you know, like the special ability soothing voice).
Note that spell calm emotions neither erases memories nor changes attitudes. If Baracs strolls into the orc camp, murders the orc warlord, is caught red-handed by the warlord's lover, uses soothing voice on the warlord's lover, and the lover fails the saving throw, the lover will (greatsword in hand) calmly discuss with Baracs his actions and impending demise as he escorts Baracs to a cell. The warlord's lover, even while affected by the spell calm emotions, can still call for help, alerting the camp, and Baracs just won't have enough soothing voices for the whole tribe. And the minute Baracs tries something aggressive (and a DM may rule that a murderer caught red-handed who then tries to flee a crime scene is behaving aggressively), all bets are off, and swords start swinging.
The spell calm emotions gives the caster a brief respite in which to catch his breath and perform some minor, non-aggressive actions, most often the spell offering an opportunity to for the party to enter into an otherwise implausible parley. It does shut down melee attackers, but while the effect lasts it also essentially shuts down the party. (That is, "The distraction of a nearby combat or other dangers prevents the ability from working.") Unless the party's worked out tactics beforehand for ambushing becalmed monsters (which is at least rude if not outright evil), the only thing a calm emotions effect will really do is let the user talk to one or more creatures that were, moments before, trying to kill him.
I can imagine that might be overpowered in some campaigns, but I suspect those campaigns probably wouldn't allow such a special ability to be taken in the first place.