Originally Posted by
Constraint
Lei Shen will never be a great fight for Nether Tempest uptime, obviously. Sadly, it's also a woeful fight for Arcane, along with almost every other fight in ToT. Do what he suggests, and go Frost until you can reforge/regem to 40%+ish crit for Fire.
Presuming you know the basics, such as which bomb to use for which fights etc. For some reason you're using Nether Tempest on single-target or 2-target fights, such as Twins - use Living Bomb for these. Other than that, simply lining up your cooldowns, moving as little as possible without messing up mechanics, "aggressively casting" to make the absolute most of every GCD, and that sort of thing.