Need help guys, can't seem to progress after 100 days of playing.

Stuck on a clan boss, got max 13mil on nightmare with one key. Hydra can't even do weakest chest and Iron twins max stage nine.

Strongest hero is Loki, does decent damage always. Besides him I use Kael, Urogrim, Frozen Banshee and Dhukk. Any recommendation? I can do one more lvl60 atm, thinking about Maneater. f2pfor now,so not much spending at the moment. Thank you guys!

Stuck on a clan boss, got max 13mil on nightmare with one key. Hydra can't even do weakest chest and Iron twins max stage nine.

Strongest hero is Loki, does decent damage always. Besides him I use Kael, Urogrim, Frozen Banshee and Dhukk. Any recommendation? I can do one more lvl60 atm, thinking about Maneater. f2pfor now,so not much spending at the moment. Thank you guys!