Portal of Rage

Further within are murderous horrors even greater than those encountered thus far! When we came upon them, we were not overcome with fear. No, we were filled with the battle fervor of Myrmidia herself! Our veins must have been bolstered with a heroic strength. We cut down fiend after fiend. Before we knew it a dozen of the foul denizens laid at our feet. Not a one of us fell. That is, until he appeared. A sinister creature as never before seen came upon us. Its horrid face bore the resemblance of the Grandmaster! In broad strokes he cut down the entire regiment, three and four of us at a time. I was the only to survive...

Kill all of the lesser daemons at the overlook in the Steps of Ruin until you find the Grandmaster. Speak with him.