Maybe it will be a terrible idea or Maybe I am a genius.
The points is that I lvl Up my 8s lvls mages on bursters spectres, until they are 28/30, and then I go to gazer spectre.
And I know you are asking about an EK lvl 60. So here is my idea, imbue your weapon with ice damage. Bring an Ek and a Ed to gazer spectre (they do not retarget) and kill 3 at a time. I am sure that you won't need to move from the entrance if you kill 3 by 3.
If you try this, tell me your experience.