After seeing my friend tank three bosses at once, I wracked his brain on how. Having someone using this makes perilous a whole lot easier.
Active Skills:
Payback Strike
Walking Fortress
To The Death
Counterstrike
All upgraded
Passives:
Flow of Battle
Bear Mauls Wolves
Turn The Bolt
Last two skill points are negotiable, I prefer to take both armour upgrades myself.
Gear:
If you have CaliBran then take 2 Critical Chance rings, otherwise one Crit Chance and one HoK.
Moon Axe is a suitable alternative to Caliban.
Cooldown Amulet.
Belt of Health (is their actually any other belt?)
You want the criticals to reduce your cooldowns via Flow of Battle.
Usage:
There isn't much to say here that isn't obvious. Taunt with Counterstrike, use Walking Fortress when you need to. Using Payback Strike on a target you have used To The Death on will give you a nice guard boost.
There are numerous opportunities to use Counterstrike to taunt mobs so the whole wave will come at you in dribs and drabs. You generally don't need to do much in zones 1-4 assuming your backline is killing everything in good speed. Zone 4 maybe To The Death a big guy and keep hacking on him. The real point is zone 5, where you use To The Death on the boss and keep him/her occupied whilst the others do the killing.
Levelling:
Go straight for Walking Fortress
Then get Flow of Battle
Then To The Death
Then Counterstike
Then passives and upgrade Payback Strike