Advice also requested

I'm not an expert since I just ran my first successfull B10 yesterday but here are my advice.

I run Lushen (L), Belladeon, Ahman, Shannon and Bernard. So far, I failed only once out of probably 10 trials so I'm pretty happy with this line-up. I still have to run the boss on manual though.

I know you don't have Lushen but I think it should be totally doable with Veromos instead of him. I guess the run would be safer but a bit slower. I think you priority should be to level Shannon to 5* and farm better runes. I clearly saw a huge difference when I started to upgrade a few 5-6* runes to +12.

-Veromos: I guess you are using rage because you don't have good swift runes for him but you probably want to replace that before moving to B10. SPD/HP%/HP% like you did seems the right way to rune Veromos otherwise.
-Belladeon: Swift/Focus is fine but I think you need to change for SPD/HP%/Acc%. Maybe SPD in 2 can be used for something else but I'm 100% confident that you need high acc in slot 6 to remove the buff on the giant in B10 (as close as 85% as possible)
-Ahman: you need 100% crit rate and %Hp and that's all. Pretty easy to rune. I runed mine with violent since I know this is the best choice but I suppose any set will do it as long as you have 100% crit rate. Mine is level 6 though which makes a big difference since he has almost 2X the HP of your Ahman. And more HP, more heal (and more survival
-Bernard: Swift/Focus with SPD/HP%/Acc%. I think this is the only way to rune Bernard. Again you need high acc on slot 6 to be able to apply the armor break and att debuff consistently.
-Shannon: she absolutely needs to be 5*!!! I know despair is the best for her but since those runes are hard to get (Giants only) you should maybe changer her to swift. I'm running her SPD/HP%/HP% but I know Vakhir suggests to replace the SPD rune on 2 by HP% and the HP% rune on 6 by acc in order to land the debuff. For the other set, I changed from Focus to Energy so she has more HP.

People usually recommend to have >12.5k HP on all your monster but I found this very low. With some monsters at 12.5k HP I got wrecked every single time I tried. They are around 14k now and it's much better although my Belladeon is very close to die sometimes. I would say 14k is the strict minimum imo. This should be easier for you to reach if you choose Veromos as leader with his HP bonus.

Again I'm not pretending to be an expert but I think this should do it. Let's see what Vakhir and Crystos say

Thanks, I'll work on 6ing vero, then Ahman, while also 5img Shannon....just takes me forever to 6 someone.

Veromos / Shannon / Bernard / Bella / Ahman will be much slower than bringing a strong DPS in tow, but capable of autoing much earlier.

You will need much better runes on your Ahman, however. First, he does not need that accuracy rune. Acc substats are fine if you get them, though. Even though they compete with crit/hp skillups, you get what you get, and I do not mind the accuracy I've gained at all. You would want 0 if it meant more hp for GB10, but I absolutely love provoking in pvp and ToA. Unfortunately, usually if Ahman still has to be triple blade, his rune quality is too weak to be worth using. Mine initially had to be and throughput felt crappy and he felt very slow. I benched him for months. Shop luck plays a large part in this. Girlfriend's Ahman was better in her 30s than mine was after I hit 40 and tried to make him work. He doesn't need to be insane, Bella will be picking up slack and both with good runes all around are capable of solo healing GB10, but you'll need to fix that rune and likely 6 him.

It shouldn't feel like it takes forever to 6. Are you still buying premium packs? I only level with double xp and spam refill, though I use faster farmers than your Arnold. He isn't horrible speed-wise like Dagora, a couple of my hell reps are Arnolds, and he can more easily do efficient runs, not like he was a mistake to start farming with, but that could stretch it a bit I guess. I can do hell with Veromos and opt for hards instead just because of run time. Moreso now, where more runs is more event boxes. My 6 time has significantly picked up once I quit 5ing all sorts of utility monsters and quit buying premiums. I barely ever used the swiss army knife of 5s I had built up due to the huge strength gap between them and the 6s, and it became "if I want to use it, I have to 6 it," which helps you quit opening packs. Baretta and Bernard are the only 5s I still use, and Baretta's happening today/tomorrow alongside the samurai experiment.

I scrolled and see you have Chasun. I would level her instead, keep Ahman benched for now. Veromos/Chasun/Bella/Shannon/Bernard is going to be easier to build, I've swapped in my Ahman who's on swift, sadly not strong enough violents to switch, who has almost 29k hp and 140 spd, and he doesn't do as reliable of a job (but my Chasun has skill-ups, and both are solo healing). I only have +12s on his 2/4/6, and can still +12 his 1/3/5 which were all epics, so I can pick up a new stat on them all, but he won't get much stronger til being reruned entirely. I gave him crit via only substats, so I had to arrange the runes carefully. Keep in mind that both will work alongside Bella when weaker runed, and Chasun routinely is paired with Bella in PVP. Not in GW, necessarily, not without a bigger box, but even there possible, backup healing and one's providing break and the other atk buff for a single bursty dps.

You probably know this, but you need to fix Shannon's runes. Creating a despair set with whatever runes you had that happened to be Despair is a bad idea. Atk in 2 and 6 is worse than breaking the despair set. If you don't have relevant runes, do not make a set just because you were told that's the rune set she needs. She needs accuracy, 52% more than you already have, and she has basically no hp mods. The 6 star defense rune is fine, she has better base defense than hp, I would take a def and hp rune over double hp on her for pve, no question. You will most probably not have the subs to not rune accuracy on slot 6, and speed on her doesn't work when she's dead all the time, so you'll probably have to go HP/Def/Acc. Despair helps significantly mitigating crystal stages, especially paired with Veromos, and she's usually the one in danger there, she does want despair, just not with atk runes. Mine was not safe on auto until she was 6'd. Manual was fine as a 5 star. I don't have the best runes on her though, I still need the accuracy rune in slot 6, but she's at 88 and it's only +12'd, so if I can get 35% accuracy subs between that slot and my slot 1, which currently has 3, or my slot 2, which has none, then she can either go super tanky or get some speed finally. Only +22 in subs, and when she's slower than the group her def buff keeps falling off, which is annoying, but she needs it the most (besides my Lushen, but it's fine if he dies on the boss after bursting, Veromos already has violented in a ton of dots, and he's not on Violent and like 1 spd slower than her, so they turn match). My Shannon has 15.5k hp and 940 defense and still dies occasionally on successful runs, but she never dies before the boss stage, and would be very, very, very safe manual, those are auto-level stats.

You also need to work on Bernard's speed, there is 0 reason not to have a speed rune in his slot 2. Put a non-swift speed rune there and break his 2-set if you have to, it is the most important thing you can do. Also, his accuracy is 12%, you want way, way more. His atk break on the giant can be life or death when going in with weaker runes.

Veromos needs to be fast. Spd/hp/hp is pretty ideal with him, that's what most go, whether they're on swift or violent. Violent is better on him, of course, but raw speed's consistency with faster cleanses and faster time 'til more dots and more stomping is still the best you can do 'til then. He just needs more spd subs and a relevant set bonus. Completing the rage set on him is irrelevant. He only needs swift or violent. I initially tried Despair, but it simply didn't feel as good as faster ones. I had a swift and a violent one repped, both with great runes, and they were just... miles ahead of Despair. Despair felt like a crutch, even in ToA, especially once his skills got raised. The speed is too strong cleansing or getting back to his more reliable stomp. I was slower, like 140 or 150 speed, under despair, and there is no comparison between then, with poor skills, and 172 spd as violent. I have used a violent one that's spd/hp/hp with over 200 spd and acc cap and it was heavenly. You need to work with what you have, which likely means swift. The faster he is, in your case, the more likely he's clearing def break before being hit. Less dangerous manual where you can smack a tower at 6 stacks until it's taken off, but still nice.

Your Bella is the rune combo I would use pre-violent, but not those stats. You may or may not go spd in slot 2 for the sake of surviving, but crit dmg in slot 4 and resist in slot 6 is basically useless. Especially crit damage, Bella is one of the weakest-hitting mons in the game, feels like he's tickling. Hp/def/acc or hp/hp/acc or something, you'll want accuracy so you can land both breaks - not as huge a deal with Bernard in the group, though very very relevant in PVP - and those siezes - huge deal to mitigate giant damage. Since Bella is so good at going everywhere, I would do double hp just because that's superior in PVP. With sufficient acc subs, I'd want spd/hp/hp as a goal. If you can really stretch it, /revenge is a pretty great 2 set for Bella, as is /Nemesis (what's nice about Nemesis on healers is the very increased likelihood they get to take a turn in retaliation to being spiked but not killed, which is true whether it was a Giant smacking during def break or a double Lushen bombing getting interrupted).

Hey as I reread this, in the last few sentences, did you mean revenge not nemesis?