Nuker Builds have to SP Farm mostly because of Knockdown and Stab Skills cause they take up alot of SP. Keep your Weapon/Fire/Lightning trees high as possible to do most damage . Rest you can put into Ice or Force. Also get aleast lvl 10 Bow Tree for lvl 1 Hawk Training for your nukes to hit peak damage more often.
I personally would go hybride. Pure Int until lvl 30 then 1:2 (Str:Int) until you cap. That way you have more hp than pures and still do roughly the same damage. Max all out your Fire/Lightning/Weapon Trees. Hope I didn't miss anything and correct me if anything is wrong. Hope that helps.
For lvl 90 cap
Weapon-----70
Fire-----------90
Lightning----70
Ice or Force-60
Bow----------10
You can increase Lightning if you want to do more AOE damge and decrease Ice or Force, but Fire Nuke will do the most damage.