Axe is one of the, if not THE, strongest hero stat wise. This is supposedly balanced out by his lack of ability. While other heroes with such a large body get a subpar signature card (Keefe, Bristleback), Berserker's Call is actually quite good. Axe excels at one thing - winning the combat phase at any point in the game.
Axe's stat line is absurd. An opposing hero needs to deal 8 damage per turn, and have at least 8 health to GO EVEN with Axe in combat 1v1, a feat only 2 other heroes can achieve... Phantom Assassin and Bristleback.
There is currently no hero implemented that can defeat Axe 1v1 and live to tell the tale.
Berserker's Call is a lot better than it first seems. It's kind of like a mega taunt, but better. It's not obvious if you read the card but keep in mind your hero DOES NOT DIE MIDWAY. It will fight all targets and only die once everything is over.
Berserker's Call can easily represent 15, 18, 21 (or more) damage, making it somewhat comparable to Mystic Flare at the same cost. All you need is a beefy red hero. I wonder who that could be? The obvious downside when compared to Mystic Flare is your hero may not survive after, with the potential upside of massive damage output when your heroes are equipped/modified to the teeth.
'Does Berserker's Call trigger X Y Z?' While I haven't extensively tested this, not all combat mechanics work during Berserker's Call. Notably Siege does not and Retaliate does. I'll compile a list of these once I have access.
Axe really isn't the kind of hero you would build around, or even require any kind of support cards. His mere presence is an existential threat to your opponent! As long as your deck has Red in it, Axe should be very high on your hero considerations unless you're going for a niche goal.
Thankfully, Axe helps tremendously in the niche goal known as 'Winning'.