I just finished Underworld on Madness using only 4* characters... You can do it too.

[Kulimar]

I just finished underworld madness!

Pulled Child of the Damned (warrior) from my legendary soul. I was fully expecting a 4* character, so I'm pumped!

Wow, grats!

[BillLion]

Thanks!! I really needed a powerful warrior, so he fits the bill.

[Nifelheim]

I also finished game on 4star generals. And unlocked every secret stage the same day too

[jpmusic]

I'm a few missions away from finishing with 4* characters too (and the help of some powerful Troopers), it can be done but you have to spend TONS of gold on your talismans

[BillLion]

I also finished game on 4star generals. And unlocked every secret stage the same day too

That's great. I'm still working on unlocking secret locations on Underworld Hard & Madness modes, but the rest are done.