Of course a lot depends on what drives your champs, so no telling from here.  My suggestion would be to visit ayumilove.  net and look at their spider dungeon guide where they list all the champs that do well with the spider.  I do not post links here cuz they can bomb you for spamming.

Then really best bet is to just do some runs to see what works best. You can start at lower levels like 10 to help sort them out. You also should experiment with which auras work best. You will probably find that some champs may start off looking OK but then hit a wall.

We have plenty of experts here to give you specifics but even so you have to do some trial runs.

Higher level spider is about HP burn on the small spiders, TM on boss and maybe CC on the small spiders.

I am newer so do not always get the pic to the right champ.

I think i See Ultimate Galek and Mort for HP Brun, MM is great for shield if set up right, not sure after that.

I ran Melga as my shielder,Iggy for HP and Taunt, Achak for buffs CC and heals, mort and Coldheart, but this was just to complete the mission it was not fast or 100% 😀

there are three basic strategies to spider 20. you can either hit the spider with massive amounts of damage in very short order, use a lot of tm control to prevent it from ever getting a turn, or use aoe hp burn and avoid hitting the spiderlings so they keep knocking chunks of hp off the spider on their turns. based on your champions, i think your best bet is option three. i'd try something like mordecai (hp burn), scyll (tm control, healing, emergency reviver), miscreated monster (cc and shield), armiger (tm control) and you've got a few options for your fifth. tatura offers solid support and can divert the attacks off mordecai for a bit with their veil buffs, soulbond adds another tm reduction, and skytouched shaman adds healing and cleansing on top of a pretty useful aura.

Monster, Mordecai, Armiger +2 chickens

But you can thro in Apo (lead -- or HK) and Scyl for now instead of the chickens.