Tanking is indeed an "art" - to gather and hold agro while your mid and back lines do the damage and support. The thing about tanking is that you don't "need" to do major damage - the tank should be there to keep the mob occupied so defense is priority (as opposed to a pressure damage dealing warrior who is not there to tank, but to distract and wreak havoc in "their" back-lines!). It is best left to a human player as it takes micro management to have a hero tank correctly, and henchies are useless at it as they don't have the same controls so will go after which ever foe is targeted by the player in control.
A tank does not necessarily have to be a warrior either, my monk and necro tank very well in duo runs - you just need the defense skills. As a smiting monk playing with hero and henchies - with careful flagging and control of the rest of your party, YOU can tank for your group. But they don't "get it" as far as agro ranges etc are concerned lol. So the foe will break agro from you and still go after them.
While playing through the game with my monk - just with hero and hench - I didn't bother with the niceties of tanking etc - I set the monks to "Run from the bugger - he's got a great big sword!" mode - and that keeps their warriors busy running in circles while I finish off their back line! It is sometimes very funny to watch Dunkoro running around in circles with 3 warriors on his tail while we pick off their monks

. The nice thing about being a human monk is that the foes will target your AI monks first leaving you free to do some healing as well as smiting.
And a smiting monk CAN do some major damage - don't let people tell you different. My brave little smiter has finished Prophesies and Factions and is almost done with NF.
Fight Well
Friday