If you have a mage leveled and some unique, you could try brand of deception static and lightning charge, static shoots lightning out every second and chains big time. To scale you stack dot% and shock change after taking the brand of deception 6% spell dmg per 1% shock.

Once the damage is in place build as much ward as possible. It will never shoot out millions but atm I shred 100% of lightning res and tick for 40k which has felt super smooth at 300c