Added after 4 minutes
Guys, try taking two heroes with 0 attack and 0 defense and give them two archangels against 2 behemoths, or 4 phoenixes against two behemoths, or 2 dragons against 2 behemoths, or 4 phoenixes against 2 archangels! See what happens!
Added after 1 minute
I think the strongest level 7 creatures are archangels and behemoths.