1/ The only weird thing about all your encounters is the 13k poison damage from SW. Your hero gotta be a joke to be taking that much poison, or most likely, you are mistaken between poison and hex damage.
2/ The archer trigger squad is the easiest opponent you will face at high-end Arena. Its funny you cant even handle the basic Arena opponents, yet you're so confidently accusing the AI of cheating.
"They always hit my weakest hero!!!" Have you thought of placing a counter Aura hero in this weakest spot? " When hero get hit" and "When allies get hit" auras are your answers! Go to http://www.arathos.com/en/
and look them up to plan your squad.
The AI is so predictable, that the only real tier in Arena is Expert1, or above 3600, because this is where pure stats trumps over strategy. I consider everyone below 3600 to be newbies who lacks understanding of the game mechanic.
3/ There's no such thing as "Elven Might" for Arena. Each of them can be a key piece in a setup, but they're rubbish when put together, simply because all of them are considered "2nd round" hero for Arena, and they need the support from other factions to be useful in the 1st round.