I got through it on manual with a team of Sethallia, Scyl, Tayrel and Coldheart all fully built, plus a half-geared level 50 Seer, whose karma burn wasn't very impressive, but her weaken was vital for CH's heartseekers to do the real work. The team wouldn't have lived too many more rounds, but that was enough. She is quite squishy if you can do your damage fast enough to keep her from healing up a lot. 

So basically you need a combination of strong heals/cleanse, debuffs and max HP damage. At least on normal, it's not the end of the world if you reduce TM and get counterattacked a few times. 

But yeah, I do agree that the difficulty compared to the 'lava doggo' is pretty steep and toning down one or two things, while turning them up on him, would be an improvement. 

What is the team you are using?  I didn't find this spider that difficult, but it was a slow kill.  I think I just threw 5 magic in so that the spider would weak hit.

Some other suggestions after another two goes: reduce speed and heal reduction are very good debuffs to put on the big spider, while the spiderlings become almost irrelevant if you have an AOE buff stripper to just remove all the counterattack buffs - or someone who can AOE stun, freeze or otherwise keep them from actually counterattacking. 

Sorry, I think I was talking about the wrong spider. You were referring to the frost spider which is void, correct? That one is tougher. I got by floor 40 on hard, took 9 minutes. 

No, he's talking about the nether spider on floor 90 normal, the one with the poison and the counterattacking spiderlings. 

On manual, I finished this floor in 56 seconds with Coldheart, Royal Guard and Armiger as my nuker. 

My auto team here is around 3mins. If I remember it correctly, I use Arbiter, Armiger, Lyssandra, Lugan and Vrask. The logic behind this team is to keep decreasing turnmeter (to not let the boss summon the spiderlings if possible) and let the boss counter attack my Lyssandra and Armiger while the other 3 champions will keep on healing. 

This is the first time I have to think the right team in the boss level where before I just put bunch of nukers then auto :D

I can see that this Spider can be a challenge to most players when this boss is in higher floors of hard mode

That's the problem: I don't have coldhearh. It also seems that her turn meter dmg is somewhat broken: by using Big Un's A3 the dmg seems managable, same with Lyssandra's A3. The real problem is using her A2 which for some reason seems to reflect like 3x the dmg it should. I tried to remove ~30% turn meter with A2 which on A3 would be about 20% of Lyssandra's hp, but then she just get's one-shotted. 

Hell Hades suggested a team with High Khatun (or Apo, for speed boost), Scyl, Ghrush and either 2 Armigers or 1 Alure.

Scyl for decrease speed, revive and turn meter as a bonus.

Ghrush for Leech debuff. Decrease tm champs heal back damage Spider do.

Spider never takes a turn.

If you are past Ghrush in daily login rewards, you are good to go.

I've beaten Hard stage 20 with 4 champs in Lifesteal set from my CB team (Tayrel, Bulwark, Grizzled Jarl and Frozen Banshee). 

Grizzled Jarl is a source of Heal reduction. The rest live forever with Lifesteal. Atk down may have helped too. Single target attacks on main Spider only, had to manual for that.

I literally just finished this stage on Hard and it definitely isn't for everyone. I did it (on multiple attempts) with Alure, Apothecary, Arbiter, Royal Guard, and Scyl. 

Alure kept the Spider from ever taking a turn, 

Arbiter and Apo was there to boost TM and keep Alure alive

Scyl was needed for Decrease TM and Decrease Speed (Also backup revive)

RG was for Def down and nukes.

It can be beat- you just have to strategize around the boss' mechanics.