The Chosen Ones

Just when I thought there won't be any fights tougher than Yurgimar, I get Zylcious.. 4 stages is crazy, and that last one is so difficult without preparation.
This guide helped a lot though.

Edited: Not having enough Honor to upgrade Impale, and none of my Heroes' skills have max HP% dmg, I was left hopeless in front of Zylcious who has millions of health points. I don't want to give up, I've killed every elite and epic so far, and Zyl drove me to frustration. However, I realized that there is one way to kill him, I still possess.. the one and only.. Poison Sting! After some calculations I realized that for poison sting alone to kill Zyl, it would take exactly 13 minutes of running away, and here I am! Finally, the bastards down! This mission reminded me of the last mission in The Frozen Throne, difficulty-wise. They're both oh so frustrating. Thank you Aero for such a challenging and pain in the butt fight.