alure, apothecary, coldheart, armiger, plus someone to get you through the waves. nethril would be ideal, but you can experiment with other champs if you dont want to wait until youve finished building him. scyll could also work if you opt to forgo damage for survivability. for the third round, deactivate armiger's a2, coldheart's a2, alure's a2 and a3, and set apothecary and coldheart to open with their a1.

you may also want to take a look at regearing some of your champions. if your deliana is anything to go off of, then i would suspect build issues to be a major contributor to your current struggle.

Any idea on which sets to use?

A big problem I have is surviving the trash mobs, especially with Coldheart and apothecary (right now I have 3 Speed sets on him).

short answer? none. i can give you the whole stats over sets spiel if need be, but i feel like you've been around long enough to have heard it already.

if you're really struggling with the mobs, you may be better off abandoning the tm control strategy. you'll have a longer run time, but that's still better than a loss. if you feel that's the way to go, i'd suggest skullcrusher, scyll, apothecary, coldheart, and either nethril or ronda.

swap apothecary with ronda.

ronda should be set to open with her a1 on round3 and default after that, alure should be set to use only her a1 on round3, armiger should be set to only use a1 on round3, and couldheart should be set to NOT use her a3 on round's 1&2, and set to open with her a1 on round3 then use her a3 whenever available.

and then throw in scyl or someone for survivability.  visix is good but she's not built yet.

scyl/ronda should take care of trash waves, you should get 10 hits to take out FK's shield, and have plenty of tm control to keep him out.  assuming your champs are fast enough, armiger has 100% cr, alure has 100% cr and high acc, and ch has 70% cr and decent acc.  aim for 220acc and you'll be good through stage 20.

Strongly disagree here. This is an overkill amount of TM manipulation. You don't need 4 champions dedicated to that.

Alure + Coldheart should be enough. If they're not fast enough, they won't fully lock out the FK. That's fine as long as you bring healing and revive. The other 3 champs should be Scyl, Ronda and a flex slot, somebody who either controls waves (M monster?) boosts speed (High Khatun, also for the aura?), or sustains your team (UDK?). You choose depending on what is killing you.

Thanks a billion, the Alure/Coldheart/Ronda/Scyl/Khatun finally worked.

Hopefully the Spider won't be as hard, lol. 

I know this is not what you want to hear, but - you really need to stop focusing on the missions. The rewards you get are not very significant, and spending so many resources trying to get through them means you are not spending them in areas that will actually progress your account.

You need to focus your resource-use better. Assuming you have Dragon20 on farm, you should literally not be spending resources anywhere else, with the exception of the daily/monthly campaign battle requirements. Everything else should go into Dragon20 farming, until you're able to outfit your teams in proper gear.

I know, but I'd really like to unlock Arbiter. 

But thanks for the tip anyway.

She's vault-fodder at this point for most accounts - likely yourself included. There are possibly a few places where you may find her useful, but by and large you won't be using her in most places.

That's a bit harsh, but fair I guess. Anyways, progress missions give a sense of progress, and encourage you to explore the game more. Nothing wrong with that.

Absolutely there is something wrong with it, if it is taxing your resources to the point of preventing your gear progress.