You've to be level 45 at least .
first go and speak to the little gnome before its house near the water in talrim ...
You may be able to do the first part at level 45 .
you've to kill 6 masters in 6 different zones . talrim (upside the manor). frostbite (on a hill .... difficult to say you exactly ..)
anidaen forest Mount zharim Jakreth and the Swamps ...
keep their sleeves in your inventory ..
ONce you've got all those go back and speak to he gnome .. you'll have the second and more difficult quest ...
you've to go to EW ... from kauldur go upside the first mountain before you ... speak to the keeper .
Then use the horn given to enter the arena ... Here you need to speak to the construct . but the nobs are 42/42 at the beginning and the last one is 50/50 .. so don't go there alone aor with a thougher player with you.
Kill the Champion and get the trophy back to the gnome... here you've got the combat casting skill!!!!