I know a lot of people won't be able to relate to this...move on lol.
I'm in the position of not being able to complete this achievement. I've tried 7 days in a row now and I can't do it.
I can't get all my heroes killed before the end...here's what I've tried;
1. Using 1 hero per floor and not using special attacks unless the special attack will not hurt the defence
2. Putting in heroes to the floor I know will die quickly
I've not been able to have all my heroes die before the end, I usually get to the top of the tower with still around 6 heroes alive...
So how did you do it when you have a full hero roster, most 6* FA and decent runes on most heroes...
Level 70 - IGN - Metafrey