Not altogether easy, but this is a working suggestion:
http://nwn2db.com/build/?223910
It has the FS essentials of Expose Weakness and Epic Divine Might, so it's a good damage dealer. In addition, it has epic mass heal and the normal divine spells for healing to provide that "powerful healing" trip, but also automatic silent 0-6 for all your buffing spells. This is to use a summon, cast silence on him (almost always a success even with your low DC, or always a success on a fellow melee party member), then enter melee. This will create a zone of silence around the summon/party member, which when near a caster, shuts down spellcasting. Well, except for yours.
This works in a similar way if another character casts silence on you...it makes you into a force to be reckoned with against spellcasters. The first feat is left open, it's actually improved counterspelling. Now, divines don't make fantastic counterspellers because they lack mordekainen, but it will shut down some key spells. With improved counterspelling all you need is a spell of the same school but one level higher to automatically succeed.
Since favored souls can cast any spell on the fly, you can also counterspell on the fly. Favored souls get too many spells, so some sly pickings will make you really good. Like, some of the most used arcane PvP spells are lesser breach and bigby6 (quickened). As long as you've picked lesser mantle (against breach) and word of faith (against bigby6), you can automatically counter them since they're of the same school but one level higher. Ethereal jaunt is a great pick too, that makes sure people and monsters can't start combat by hiding from your fury, and enables you to get away in a pinch.
Why the quicken spell? Well, to cast lots of silence around of course, and enable extremely fast buffing if need be (like, after getting dispelled). Remember, you're almost immune to silence, so extend and quicken them all around you. When cast on the ground, there is no save, and the area of effect is a bit bigger than the cursor will show you.
What are the downfalls?
Sadly, you kinda need a water domain deity, or else forego epic mass heal (by picking evasion class 3 levels, cleric 3 levels, 24 favored soul). Silvanus is cooler, but you get weapon feats for warmace that way which isn't ideal since you've no twohanded weapon feats. Istishia however is perfect. Warhammer is one of the best weapons there is for a favored soul, with their ability to get keen on it for free. Another option is getting auto silent 0-9 instead of epic mass heal (which isn't super good atm). You won't get too many skills either, just enough UMD for wands with a +2 item or heroism and the typical spellcraft/concentration combo you need.
All in all, it's very solid, still super strong, and quite different from the other run of the mill favored souls out there. You may have a point or two lower AC, and do 1-2 less damage on -1 AB compared to them, but you've all the other aces up your sleeve as described above.
Let the build serve as an inspiration
