I think the best bards are pure bards (1 more reduction to fort and reflex save on curse, 1 more SR drop on curse, 1 more AB from song, +15 stoneskin vs. +14 which is a big deal -- bigger than I think a lot of people realize, 20% more GV duration, and 5% more conceal), but as always there are compromises, mainly that you have to work hard to get saves up while with Paladin they're super high for free. For new players the Paladin splash is easiest.
When I built mine, 36 base CHA was the target, and I met that. We've all heard rumors of upcoming changes that will encourage higher charisma, but nothing solid yet. I have found that ~20 base STR and DEX have helped my bard stand longer when Hells KD critters are around, though not immune. It's a tradeoff, and if one wants 48 base CHA there's no way to get the extra points for STR and DEX. That's fine, just be aware. I'll also agree that without a fancy subrace it would be exceedingly difficult.
Even with a 36 base CHA, I think even just 10-20 points in taunt would let you taunt a
lot of things even in the Hells. Definitely concentration, discipline, heal, parry, perform, tumble, and UMD.
Definitely agree on ICC for healing circles. Legendary Illusion is a must -- it will help you survive via conceal, it will help your displacement buff on tanks, and it will make your Ghostly Visage last longer. Since this build will have both legendary enchantment and epic transmutation, you can do +14 GMW and keen
all weapons. Use this on your party members -- it will result in a lot of extra damage on many things and make for very happy tanks.
If you have the
HG Enhanced hak, which you ought to get, I think taking Extend instead of Silent is a better deal. With the hak you can extend any spell. You do lose the ability to cast spells when silenced but this is very rare, and IMO the advantage of having extended GV, extended Displacement, extended Expeditious Retreat, and so on is going to enhance your enjoyment of the character a lot more.
Some of my opinions on bard spells:
Important spells: Energy Buffer (6), Ice Storm (6), EV (5), Healing Circle (5), GMW (3), Keen (3), Displacement (3), Clairaudience (3), Clarity (2), Ghostly Visage (2), Expeditious Retreat (1), Mage Armor (1), Balagorns (1).
Some additional spells worth considering: Dirge (6) (without spell penetration it's really iffy), Mind Fog (5) (DC is terribly low though), Greater Dispelling (5) (strips some buffs off enemies), Legend Lore (4) (useful for ID'ing anything even with Hells penalties), Wounding Whispers (3) (for the 20% sonic immunity).
Buff people without conceal (e.g. str tanks and clerics) with displacement. Give out the Clairaudience buff to anyone who maxed Listen (though without Divination it won't be huge). GMW and Keen on tanks. For myself I use Etheral Visage (5), Energy Buffer (4), and Extended Expeditious Retreat (1) (fast movement on a caster bard is very helpful). In Hells if I bank I will also cast Legend Lore (assuming you have it) to add 30 to Lore, allowing me to ID anything even with the penalties.
Now I'm going to indicate some ways you can play. There are other ways to do it (for example Mish plays his bard quite a bit different than mine, but very effectively). If I may rant a little, there are a lot of caster bards out there that don't have a clue how to play their characters. They sing only when they've been begged 5 times, they curse late if ever, and after that they just stand around doing nothing. What a waste of a good character. Bards are not just Possum/song-monkeys.
IMO your base job is to make sure everyone has song and enemies are cursed. Good bards will notice if someone has died or rested and make sure they've got song. Occasionally they'll even ask if anyone needs it. They'll find out who needs buffs and make sure they have it on them through the run. I can't tell you how nice it is to be a str tank in Hells and after death or rest to get song and displacement without having to ask. In the Hells this is
really important -- no tank is going to go anywhere close to Asmodeus without bardsong to get their AC out of the gutter. At high levels you'll be able to be spawning things even up through Malbolge in the Hells, getting them cursed, then (using your high level expedition retreat) zipping back and supporting the party. Alternately you let a tank spawn with you behind and then curse them. You'll want to keep looking to make sure things aren't running around uncursed (you really need the enhanced hak to do this effectively). With your ability to use Greater Sanctuary (via scroll), extended Ghostly Visage (10 rounds of GS with no timer), fast movement via Exp Retreat, and ability to use blade scrolls, you make a real good puller.
OK, so you've made sure your party is buffed, and everything has been cursed -- what's next? You could taunt something to lower its AC even more. If you have a Turner and you think your Mind Fog is effective you might use that (you could even send them tells to talk about it). If you're in the Desert, Ssithrak, or Illithids and you're level 50+, try out Balagorns (1) -- at high levels you can KD a lot of things. If things need gusting, maybe you could do that. If someone is stoned, read a stone to flesh scroll. If a black blade would be helpful, pop one up with a scroll. Mindblank or Clarity people as necessary. If needed use a restore pearl on the shifter, BFM, or a tank. If someone dies, rez and re-song them. Check out the party health using the icons -- you will eventually have a LOT of healing circles and you have maxed heal. Just standing near people for the next 10 rounds after casting it is going to give them +40 or more regen, plus you can do another HC to hit everyone nearby with up to 600+hp of healing. I've found that staying up near the tanks and giving them this healing helps the party quite a bit. You can always use GV if you want to stop things from hitting you if you're just doing healing circles. I'm not personally into using ice storm a lot, but don't forget that you have it available. If things start getting too hectic, hit the hotkey you have setup for extended Ghostly Visage -- you now have a full minute that things aren't going to hit you even if you're KD'd. You can rez, sing, buff, cast healing circles all without worrying about what monsters you're standing next to. Don't over-rely on it but it's there.
As for epics, you have Possums which is one of the top epics in all of HG. Make sure everyone's back from rest and use it. Sometimes if we've had a bad random and lots of people died/used it, I may rest a bit early to get everyone fresh again. People use UUU (the transmutation epic) differently. In LL areas it's often used as a quick infusion of 1000hp. For the Hells this is, in my opinion, a misuse (e.g. the bard that always fires it off as part of buffing). For the first 3 levels of the Hells (Avernus, Dis, Minauros) you ought to use it any time there is a Pit Fiend or Malebranche. With random spawns there's a chance at any time you could get one, and having that quick UUU to keep people from being knocked down can cut down stress from that random immensely. For Phleg and lower it's really going to take some thought and party discussion to figure out when to use it. IMO you want to use it if the KD critters are seriously all over the casters, or if you get a mixed spawn (Pit Fiend and Malebranche at the same time).