Diona is a bow user with a Cryo element. While her normal attacks are nothing to write home about, her kit can be quite useful as a support. Her shield strength scales off of her max HP, and the duration is based on tap or hold version of her elemental skill. Her elemental burst deals damage and heals you every 2 seconds for 12 seconds. Since it also applies Cryo element every 2 seconds, it's useful for elemental reaction with your team. Her main downside is that her elemental skill has quite a lengthy cooldown, and elemental burst is costly at 80 energy to use.
The best weapon to use for her is the Sacrificial Bow. It adds a lot of value to her since doing the hold version has quite a long cooldown, but it gives her about 4 elemental particles, and another 4 if it resets again. The shield duration also stacks if you do the tap twice when it resets, becoming around 8 seconds of shield. However, the shield duration can't go over 12/13 seconds, so holding down the skill twice will only stay at around 12/13 seconds.
Normal Attack and Aimed Shot hits increase ATK by 4% and Normal Attack SPD by 1.2% for 6s. Max 4 stacks. Can only occur once every 0.3s.
There are several good 2 piece artifact sets that you can use for her: The Exile and/or Scholar, or Maiden Beloved. Use the ones that will fit your play style. Using a 4 piece set of any of them is also not a bad choice. The main recommended thing is to go for HP% main stat for your artifact pieces for increased shield strength, and a Healing Bonus% on the crown piece for her elemental burst. Energy Recharge% on the hourglass piece can be an option as well.
If you want to go for damage dealer instead, since her skills have a lengthy cooldown/cost, normal attack spam might be the better option. Go with any 5* bow for higher attack, or Rust. Compound Bow for free option. For artifacts, go with 2 piece Bloodstained Chivalry with any other 2 piece +18% atk, or go with 4 piece Retracing Bolide. The important one being Physical DMG Bonus % on the cup.
Using an Elemental Skill or Burst increases healing received by all party members by 20% for 10s.
She works quite well when paired with most main damage dealers because of her Cryo elemental reactions, and her skills can be fired off pretty fast, while also not requiring her to stay on the field for continuous Cryo from her burst.
Diluc can cause 3x Melt reaction when used together with Diona's elemental burst for a significant damage increase. Razor's electro element is good with Cryo since it reduces enemy's physical resistance. Keqing is similar to Razor, but it will mostly help her if you go with mostly physical attacks.
Chongyun has trouble generating his own energy, so you can put Diona on the team as a sort of Cryo Energy generator in addition to her support kit. Having two Cryo characters will also give the Cryo Elemental Resonance for additional Crit Rate.
Fires an Icy Paw that deals Cryo DMG to enemies and forms a shield on hit. The shield's DMG Absorption scales based on Diona's Max HP, and its duration scales off the number of Icy Paws that hit their target.
Press Rapidly fires off 2 Icy Paws.
Hold Dashes back quickly before firing five Icy Paws. The shield created by a Hold attack will gain a 75% DMG Absorption Bonus.
The shield has a 250& Cryo DMG Absorption Bonus, and will cause your active character to become affected by Cryo at the point of formation for a short duration.
Regenerates 15 Energy for Diona after the effects of Signature Mix end.
Shaken, Not Purred
Increases Icy Paws DMG by 15%, and increases its shield's DMG Absorption by 15%. Additionally, when paws hit their targets, creates a shield for other nearby characters on the field with 50% of the Icy Paws shields DMG Absorption for 5s.
Increases the Level of Signature Mix by 3. Maximum upgrade level is 15.
Wine Industry Slayer
Within the radius of Signature Mix, Diona's charge time for aimed shots is reduced by 60%.
Double Shot, On The Rocks
Increases the Level of Icy Paws by 3. Maximum upgrade level is 15.
Cat's Tail Closing Time
Characters within Signature Mix's radius will gain the following effects based on their HP amounts: 1. Increases Incoming Healing Bonus by 30% when HP falls below or is equal to 50%. 2. Elemental Mastery increased by 200 when HP is above 50%.
A Stella Fortuna is required to unlock each constellation. See Constellations Guide for more details.