Odette

5★

CryoSwordOff-field Damage

TL;DR

Odette's Skill leaves a dancing copy of herself on the field that keeps hitting things with Cryo for about 20 seconds after you've swapped away. For six seconds after you cast it, that same button turns into a second, much bigger version, so press it twice. She also collects a stack of buff for the new Stellar reactions and hands it over to your team on the way out. Two presses and a swap.

Rotation

Swap in and press Skill (E).
Press Skill (E) again immediately for the second version.
Burst (Q) if it happens to be ready.
Swap to whoever is doing the damage and leave the double running.

Abilities

Skill (E)	Cryo damage, and it summons her double for about 20 seconds. For six seconds afterwards this button becomes a longer dance that ends in a heavy hit counting as a Stellar reaction. About a 15 second cooldown on both.
Burst (Q)	Costs 60 Energy. More Cryo damage, re-summons the double, and boosts the Stellar reaction damage she personally deals for about 20 seconds. It also opens the same six second window on her Skill.
Her stacks	Summoning the double gives her four stacks, each worth about 15% more Stellar reaction damage. When she leaves the field she drops them at one a second and your team picks them up.

The one mechanic to understand

Stellar reactions.

With Odette in the party, two ordinary reactions get upgraded. Superconduct becomes Stellar-Conduct, and Cryo swirl becomes Stellar Swirl. Both of the new versions hit far harder than what they replace, and every scaling bonus in her kit points at them. So she needs an Electro teammate for the first one or an Anemo teammate for the second. One of the two, not both. Give her neither and you have a Cryo character with a summon and no reason to be there.

What actually matters

The two or three real decisions. Everything else is noise.

Press the Skill twice. The follow-up version is the bulk of her own damage, and the window for it is six seconds. Casting once and swapping away throws away most of what she came to do.
Attack. Her passive turns attack into more Stellar reaction damage for the whole team, and her own hits scale off it too. Somewhere around 2,500 is a comfortable place to land.
The Burst is optional. It's a decent chunk of damage and a solid buff, but she does her job on the Skill alone. Build Energy Recharge to cast it when it's convenient, not to force it every rotation.

Gear

A build that works. KeqingMains lists every other option.

Weapon	Attack first, crit second. Finale of the Deep is craftable and piles on flat attack, which is exactly the stat her buffs read off.
Artifacts	4-piece Heart of the Furnace. It boosts Stellar reaction damage for everyone nearby, not just her, which is the better half of what she's for.
Main stats	Attack sands, attack goblet, crit circlet. A Cryo damage goblet does nothing at all for the Stellar half of her damage, so don't be tempted.

Works well with

Electro

Anemo

Electro turns Superconduct into the upgraded version, Anemo does the same for Cryo swirl. Pick whichever you already own.

Don't bother

Normal attacks. She's on the field for about four seconds and none of them are for swinging a sword.
Counting the stacks. Summon the double, swap off within a few seconds, the team has them.
Elemental Mastery. It reads like it should matter for a reaction character and it loses to crit and attack every time.
Running her with neither Electro nor Anemo because the Cryo application looks handy. It isn't enough on its own.

Want the full theorycrafting version? Read Odette on KeqingMains.