Tal'Dera

Tal'Dera is the most min-maxed unit in the game - almost to the point of detriment if not for one thing - Divine Flow. Due to T'D's stacked passive, she can actually sustain Divine Flow pretty easily and because it stacks, she will almost always be safe unless she goes against an enemy empowered with "Guaranteed to hit." Her pitiful Mastery stat limiting Divine Flow is what holds her back from being higher than B tier, but as long as you don't throw her against a mass amount of enemies where her Divine Flow is exceeded, she will carry. 

At level 30, you generally have about 10 more levels to go. Unless you are favoring a character or farming a lot, You generally won't make it much past level 40 - MAYBE level 45. At this point in the game, look at the character's bases compared to the growth rates. For every 10% of a growth rate, just add 1 point and you'll have your level 40 endgame stats. 

Ascendant - This is without a doubt her best class. With her min-maxed statline, going into Ascendant let's her only weakness - her lack of any defensive bulk - not really matter. Spam Divine Flow when you have the mana as its stacks stack and let her min-maxed statline carry her the rest of the way. Give her the Dominator Ring as she won't be getting hit and needs crit for mana back. Use Competitor Ring for some extra power or Hurricane Ring to help get around the battlefield. The Heir and Mystic Ring will also slightly increase her Divine Flow stacks if you have no other user for them, but generally those are best used on other units.

• (Conduit) - The Conduit will give her access to more crit and in Demonic where enemies have high crit resist, that's something important for her. Arguably her best tier 2.

• (Frigillan) - The Frigillan can give her access to 5 more power permanently as long as she has some form of block. This should easily be up 100% of the time. The Icy Spire is also decent situationally, but we're really just after that free 5 power here.

• (Gale) - The Gale gives her access to toggleable magic damage on demand with a debuff cleanser added in. Ravaging Winds is also really decent when you can get it to line up just right; however, with her Divine Flow, she won't be taking the hits to really capitalize on it. 

Tempest - Due to Tal'Dera having the most min-maxed offensive statline, she can become quite the dodge tank. With the Monk as her tier 2 class, she can hit pretty decent numbers with Charged Ki. She has pretty high dodge when Charged Ki is active and unlike how she really just wanted to use mana for Divine Flow in Ascendant, she will have mana to spare for other things like Steal the Stage and Swift Winds. Due to her relying on being a dodge tank, the Chosen and Victorious Rings are really decent combos as they all but guarantee she survives at least 2 encounters even with bad RNG. If you need more dodge, you could also try the Depth, Diplomat, and Drunkard Rings. Additionally, because her statline is so min maxed offensively, she is a good candidate for Bloodied Ring to push her in to absurdity. Unfortunately, Tempest (along with Ascendant) is locked to 1 range and not ideal on Demonic due to the higher hit rates making her above average dodge almost meaningless.