Off topic, but you can one shot the spider queen by shoving her into the underdark. Shoving from stealth or invisibility has 100% success chance. I did it by accident during the fight so I do not know if it works from her initial position. Shoving her from the pillar into the hole in the ground did 205 damage and I found her corpse in the underdark.
I guess its known, but a perfect display of what the game's difficulty issues are
Sounds fun at first, but again this turns the game into a 'goat-fight' (whoever here came up with that term - cudos to you, perfect summary of the mechanics). Classes are meanlingless. Skills are meaningless. Just be invisible and shove the enemies of the cliff with 100% chance.
Invisibility shove was changed as of the most recent patch. You lose invisibility when you shove and most shove paths of instakill cliffs aren't valid anymore. Most reliable way to get the Phase Spider Matriarch down the hole now is to lure her to the lowest web over the hole and destroy it while she's on it. If you never want any other fights to be hard, Getting her down the hole is the easiest way to get her on your team with Glut, and I think she's the best monster you can get on your team this patch.