A booked level 60 UDK in toxic gear can solo it, slowly, with 4 chickens

that would be pretty funny, but they keyword there is "slowly" lol.

IIrc it was about ~7 minutes per run on stage 20 when I used to use it

lame153 is correct. When first climbing IG, it is much safer to rely on poisons & burners versus straight damage.  

Frozen Banshee is an awesome poisoner for Normal IG.  Venomage is a strong alternative who also does Dec Def & Dec Atk....although you may not want Dec Def, depending on who else is on the team. 

Scyl & Stag Knight are both incredible progression champions for an account at your level. They will help you everyhwere.  

Dark Elhain's passive will keep your toons from getting frozen.

Ultimately, with the proper gear, Venomage can solo IG quite easily, and fairly quickly too. When I used to do that, I think it was around 1:30 to clear.

First of all, I notice you have Kael and Athel, but neither are maxed; you might want to focus on doing that, especially with Kael.

Anyway, for Ice Golem 12, I personally use Sun Wukong, Loki, Alice, Fylja, and UDK, but I'm pretty sure Ronda CH, and Bowyer work pretty well too. If you can end the battle fast enough, negating the revive effect isn't really necessary. 

Given your account's champs and using that to estimate your gear, I'd say your best bet is a non-solo setup (though the UDK one is still possible based on what toxic gear you have).

My recommendation would be Vrask, Ninja, Scyl, Toragi and Doompriest.

Doompriest will autocleanse the freeze and get your Inc Atk for Ninja

Toragi will offer survival if boss does full hit with both adds up AND will get poisons on him

Scyl is healing and a rez, also dec speed

Ninja is where all the damage is gonna come from, especially his A2

Vrask needs to be in 4 or 6 piece retaliation with 100% Crit rate (so crit rate gloves) and as much HP as possible. His only job is to crit either on his turn or counterattacking so that he gives big heals. he needs zero books or scrolls.

Last piece of advice is not to bring Gnut. He'd do awesome damage but he'd also trigger the boss multiple times in a row and you'd wipe. He will be a MVP for Fire Knight and Dragon tho.

Meh, Kael is overrated imo. There are plenty of other champs who do what he does, but better. I have the same opinion about Athel, but people don't overhype her as much lol

Anyway, I tried the poison strategy again because I didn't realize poison damage doesn't proc his Frigid Vengeance. (thanks lame153, not sure what happened to your post) I used UDK, Banshee, Venomage, Fellhound, and Ronda.

I think my problem is I don't have a good way to get enough poison debuffs on him. I can't survive for as long as it takes to whittle his health down. I tried Aothar, but his A2 picks targets at random.

I'm also having trouble clearing the first 2 waves if I focus on poison champs. 🤔

And thanks everyone for the other suggestions! I'll try those at some point as well

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