2 attackers, a warrior using protect > 50% + taunt can do it. The warrior has to be exactly in that spot, it should be the edge of the inner circles while Medusa is casting petrify. If the warrior is right placed it will simply keep the aggro and Medusa won't be able to attack during petrify time. Thats 1min Zerk without any interruption. The old "csro-like" bug does not work anymore. During "bug" you can't use any low range attack skills, because you have to be a bit more off than the warrior char. If you put the warrior to side you can also escape Medusa's tail attack, while the cleric stand in center and heal all 3 chars
