The part where you have to play through Episode 11 again is pretty stupid. At the same time it saved my ass on the second playthrough because the game only let me revive 3 Thanes. I was able to restart and bring all my thanes with me to this part.
This tip is awesome! The only thing was my spear broke on wave 2 (wtf? legendary weapon?). I found if you stand on the ramp and go into carnal and just press x one push at a time (no combo) it works great. Also I got my boulders to 80% ish in between waves.
Gotta love that this 98% of this forum only follows current games. No one remains active in forums of games they've finished. Good luck getting achievement tips for an original release.