Now skills mp will scale with your level so no big deal here, unless of course you have burnt all your mana then too bad.-Depending on your mp pool
Enmity should be less of an issue with skills that scale this includes ones that generate enmity on GLA and MRD.-Depending on the enmity you want to generate
I assume this is solo, you shouldn't be fighting monsters much more powerful than yourself anyway. (if you are then expect to take a beating or come close to death)-Depending on the time you can allow yourself to be defenseless while casting
Personally I always follow up my nuking with a sleep spell when soloing, does the trick.