“Approach the massive Vex Gate at the top of the Endless Steps to lure the Gate Lord.”
Head down the slope or just over to the edge. If you like to snipe: edge. If you want to fight through: path. You will encounter a large number of Goblins. Mixed in are a few Hobgoblins. Clear the area and stock up on ammunition. You are going to need a lot for what is coming.
When you're done deal with this initial swarm you will want to head for the center of the area. Go on up the steps and go to the massive Vex Portal. There are more Goblins to deal with on the way. There are also 2 Hobgoblins at the top of the steps. They are the last ones in your way. Clear them all out. Just head up the slope and start fighting at the top of the stairs. There is plenty of cover to make this somewhat easy. Still, do not expect a cake walk here on out.