Plenty of guides out there, but the tl;dr is basically to use passive healing to counter the damage from the bombs. Vogoth is great here. Freeze works great too, if you have an affinity-appropriate one. Master Butcher is good in a pinch if you lack Vogoth.

Or block damage. It is possible to solo him with Templar.

First things first: please post your roster. 

yep that helps the most when asking for help , cuz tbh the only reply i had for OP is that i just run my 5 best geared champs for DT bosses 10-20-30 .. after that i have to change it up !

Without knowing Op's champs its hard to say if my reply wouldve been rude or not 

Okay, fine:

Edit: Of course, the game chooses NOW to refuse to load....

If you just want to do the advanced quest and aren't worrying about higher stages yet, you can try to send in your best damage dealers and just burst the boss down. This only works if you can finish the fight before any bomb debuffs trigger.

Yeah, tried that. Tried using guys that deplete the turn meter too, tried healers, tried looking up guides on YouTube (only advice they have is, "Use Champions you don't have") nothing is working.

Okay, here's what I've got.

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i

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you have Burangiri! there is a very easy solo cheese. Just stick him in a regen set with lots of hp.

I don't know if level 50 is enough to beat stage 10, might need to take him to 60.

I mean, first and foremost, by far your biggest problem is your lack of level 60s. Doom Tower isn't really intended to be done with level 50s, let alone level 40s. There are some fights you can cheese your way through, but by and large they require full teams of 60s.

For Bommal specifically, you'll probably be best off just using Burangiri solo. The gear requirements are quite reasonable for the earlier stages. See this:

https://www.youtube.com/watch?v=BC371q5XTLc

I would also recommend Burangiri and the link above. For me, he did all the Bommal stages on Normal Doom Tower and through stage 50 Bommal on Hard Doom Tower.

If you can't make those stats, perhaps you can have better luck farming the Templar from campaign and doing a Solo Templar build.

I know, I'm working on leveling commons to five, it's not difficult, but not fast either. 

Lol, I doubt I'll get to 50 any time soon, but thanks for the tip. 

One last question, what a good equip set for Burangiri? Regen, maybe?

See the video :)

Right. Btw, I did fine last month with the ones I have. This one is just... Wrong.

Edit: Huh, so that's how you pronounce that guy's name....