How much damage are you doing to the cb

12m in Hard, 9.5m in brutal

12.3 brutal.

You can build an unkillable team with Demytha and Maneater. But the champs in CB have to be lvl 60 and have full masteries to be effective. 

Campaign farming may be one of the more boring parts of the game, but you should bring Demytha, Maneater, High Khatun, Gaius, Spider (the champion, Dark elves epic) and Armiger (Sacred Order, uncommen) to lvl 60. The first 3 mentioned can be in a Clan Boss unkillable team, see here.

Gaius and Spider are more for general content. Your actual Dragon team, with Siphi, Krisk and UDK is a bit to defensive, i guess the runs take quite long.

For the Spider dungeon, you need champs that can hold the turnmeter of the big Spider down. Armiger, Coldheart and Maneater can do so. UDK to protect your team, Mordecai for hp-burn. Should work all the way to stage 25, I don't know why you struggle at stage 17. Do you use any champ to decrease the turnmeter?

can you post your gear for the champs i notice a few issues with sihpi gear and I'd love to help 

What is the best way to post gear?

I dont mind that farming, as it feels you are completing something.  Dragon 20 runs take about 5 minutes each.  I have tried to help Mordecai with that, but I dont think my top champs do this well or consistently.  I am excited to try these out.  

the screenshot you have gives most of the important info for siphi, so just repeating that with the other champions you're concerned about selected should do the trick. the only piece that's missing is the main stats on her gloves, chestplate, and boots, but you can just write that in to avoid needing multiple screenshots for each champion.

looking at siphi, i can see a few major issues. the biggest is that not a single piece of gear is at level 16. the boost you get from hitting level 16 is huge, so you're losing a ton of stats by using unlevelled. the upper row of gear can wait if you're short on silver, but you should absolutely have the gloves, chest, and boots at level 16.

you'll also want to avoid levelling or using any gear below rank 5, particularly in the slots i just mentioned. accessories are understandable given how difficult they can be to come by early on (though i still wouldn't waste silver bringing them past 12), but her boots and chestplate should absolutely be replaced with rank 5 or 6 pieces.

in terms of her overall stats, speed should be your highest priority and hers is far too low. using higher ranked boots should help somewhat, but you'll still want to try to find gear with good speed substats to increase it further.

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Krisk stats are all def% on gloves,chest, boots.

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stats are hp,hp, and speed

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HP, Attack%, speed

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crit rate, attack percentage, speed

I know these are not all the best, but have not come across better gear.  if it has good main stats, it has garbage subs.

You should never use gloves, chest or boots with flat atk, flat def or flat hp as main stat. These items only exist to be sold and generate silver. While the items in the top row have fixed main stats, allways flat atk for weapon, allways flat hp for helmet and allways flat def for shields, the items in the bottom row can have hp%, def% or atk%. And for every single lvl 60 champ, for most champs even at lvl 50, a main stat with % gives much more points for the same stat as flat versions.

Get rid off UDK's gloves and chest and Coldheart's gloves. Flat hp is a terrible main stat for bottom row artifacts. Don't use artifacts like this and don't level them up, it's a waste of silver.

Coldheart should have gloves with crit damage as main stat. Her crit rate is high enough to crit with the A3 most of the time (2 points more would be perfect), you want crit damage to make that a really strong hit.