F Corrin question?

Those IVs aren't the best. Corrin wants her defense as much as her speed and because she can show up as a 3 and 4 star unit it wont be hard to find one with neutral defense. If you really want to use her than a budget triangle adept quick repost 2 set can be used, but if you really want to invest then lightning breath can help her enemy phase. But really I would wait for a -res or -hp Corrin before investing.

+spd is good, -def is bad. not worth promoting imo.

A -def bane will truly handicap her in my opinion, I'd say you should wait for a -Res Corrin (or -Hp/-Atk to let her at least survive magical hits, even if it's not her role).
Speed and Defense are her most impostant stat with every build so you should also take one with a +Def/+Spd boon if possible ... +Atk is also okay if it's your only choice.
So try to get a +Spd/+Def -Res Corrin (the famous Gamepress syndrome, lower your Res everytime).
Now for her breath ... Lightning Breath is a really good DC weapon if you have a spare 5*Adult Tiki or Nowi ... but Dark Breath is also pretty decent, with the debuffs and attack power. Also, if you want to upgrade it, you should get the +Spd version in my opinion.
As for her build, you have :
Bonfire for her special, it's the absolute best choice. Or Ignis if you want pure destruction ... but the +1 cooldown from Lightning Breath will make it harder to activate.
Command skill : I use Swap to save my other units, but I believe Reposition or Pivot could work too
Skills :
A- Armored Blow, Fury or Steady Stance to make her tankier, or Steady Breath if you're ric.. Luckier (if you go for SB, you can go with Ignis safely)
B- Quick riposte if you want to double Brave Lyn etc ..., I use Drag Back and it works perfectly with Armored Blow, Lunge (is it written like that in english ?). Lunge isn't the best choice tho ...
C- Threaten Res, Savage Blow or Hone Atk/Spd
S.Seal - Go with Distant Def, or Speed +3. If you don't have them, Savage Blow could be usable ...
Alright that's all ! I hope I could clearly share my ideas (english isn't my primary language). Just ask if you have questions, I've been using F Corrin since day 1 so I can easily help you ^^