I just found a pretty insane melee hero combo.

[Rhalius]

Currently I have a Mystic melee hero with the executioner axe, a phase cloak, boots of freedom and she also has the killing momentum and sprint abilities, along with of course all the other melee damage stuff.

In a siege attack, she can reliably take out two units a turn, pretty strong ones too. The executioner has a chance of instantly killing any 1/2/3 tier unit.

Having the astral attunement made her even more deadly, now she can move through the walls too and not just teleport short range.
So not only is she dealing insane damage, the extra movement options allow her to never let that bonus killing momentum attack go to waste. Heck the teleport lets her reliably flank too, she can just appear behind the enemy battle line and wreck havoc.

Great thing is that she even asked for the materials to create the executioner axe through a quest, so I got her the items and she's really putting it to good use, always in the vanguard as my leader and her main army take out every enemy city one by one.

Being mystic so getting the star blades + the mana addict bonuses from that culture trait might also help.

[Primal Feed]

yup, I like using their Hero Signature Skill Draining Blade, Blink, or Demon Step. It depends what I have access to.

[Azunai]

Get her a vicious killer or murder ring to double the morale impact of the killing spree. Really effective.

[Rhalius]

She had one of those too, that both lowered enemy morale and increased ally morale whenever she killed someone.

The game concluded but I just had to make that woman a Godir herself. Vela Spellbreaker has ascended to become a champion after that campaign.
An axe is obviously her symbol and any time I'll play her I'd try and get my hands on an executioner's axe for her.

Had some trouble desciding on a culture for her, ended up with industrious, with materium and chaos focus.
Barbarian just didn't feel right for her after coming from the mystic culture and I didn't feel like mystic would fit for a champion as well. Might have been too similar to her original faction too, another faction of black skinned mystic humans.

While high culture looked alright, I just don't find order a good fit for someone with an executioner's axe as her symbol.

I'm really looking forward to getting new cultures in the future.

[アンジェル]

Dwarven Hammer + Sentinel vs. melee enemies

everything else on top is a bonus

[mabarry2]

I had Yaka (NPC character) do something like this. Watched its attack chop up two shielded units with 72-hit points in two turns. Teleported from within breached walls in front of my defense and whack, whack one defender died. My turn caused damage, which was repaired. Second turn, whack, whack and the second shielded defender died. Finally killed Yaka on the fourth turn and won the battle at a cost of 8 units out of 12. Whew! Yaka took his weapon with him into the Void. Gotta find it now.