Illya vs Goetia

Do you have Hans levelled up? He could work as support alongside Merlin, having consistent heal and damage boost if RNG allows it.

Someone with buster support is still good. Nightingale, Helena, Shakespeare, Leonidas. I also ran Illya for my own run against Goetia.

Ideally, you don't want another DPS. You just want one DPS that you can buff the heck out of.

One DPS in the front line. If you're going to run a second one, put them in the back in case Ilya dies. The best F2P support is Hans, and he has decent synergy with Merlin (helps w/ passive star gen and healing, gives sustained defence w/ Def Up on his NP while Merlin takes care of the boss' NP w/ Invincibility--just remember you'll need something different for that Turn 1 NP).

Asterios as your debuffer, his best job is vs enemies/boss that has really high hit count.

- i soloed Goetia using my NP 1 lvl 96 Heracles with his Bond CEs.
Atlas Academy Mystic Code and 3 taunter or scapegoat on the front, easy win and i reset that.
Not even a Challenge.

- Asterios + Darius + Friends Waver + Mozart + Kintoki Rider + Marie Antoinette.
I used durable team set up, of course for my breakbars training because i won't use steamroll teams like Buster Crit there.
Debuffing Goetia + Def buff from Waver ( i laugh while seeing Goetia NP damage, it's so small LOL ).
It's a pretty long battle so i will go to the ''big gun'' here. Goetia still has that nasty debuff ( Asterios and Darius doing their job very well here ). Then Mozart will buff Kintoki Rider with his guaranteed Crit + powerful Art card ( nasty NP gain so Kintoki dan use his NP again ).
If anything goes wrong and my Bond 10 Marie will finish the job, at least she can finish Goetia herself if my tactis have failed.

If i use your team set up, that would be like this :

- your Asterios ( NP Battery CEs ) + Darius ( NP Battery CEs ) + friends Waver ( more preferable )/Merlin + Hans + Illya + your Anchor ( Cavalries more preferable ).

If you can't kill Goetia as fast as possible, then just use a more durable team set up and Victory would be yours.
Use Hercules or Chu Alter solo if you got depressed or can't beat him at all.