Defiler is impossible

How do you even clear the fight? I've tried so many builds like those solo Inez videos that just melts the boss in 20 secs just with her 1st skill but they don't work. It takes 4 minutes of me running around just to clear the shields. I tried putting all HP mods and Toxic res mods but they don't work either. I'll just survive better than the rest and in the end we still wipe. I'm not sure what I am doing wrong. I have the same builds and using full slayer components and yet I'm having difficulties. I saw another post about the defiler mechanics and that helped abit but once you get hit with the poison its basically game over. I really dont know what else to do.