Free after you clear chapter 6. High mobility, decent mix of AoE and ST damage. Can push enemies into holes, dispel buffs, def shred and destroy cover (can also stun at v6).
Can't move after attack means her high mobility can get her killed sometimes if you don't pay attention (can be mitigated with dupe 1 and key 3).
Can only do good dps if you have slow on the enemies and physical dps dolls falls off in high level contents. She needs a lot of dupes to do good damage, but there are better standard option to invest dupes in.
Not good even at high dupes, you can use her if you want but don't pull her dupes.
You should only get this key if you want to use Yoohee and/or a physical team as it helps her debuffs uptime, other than that it doesn't really change much about her so I wouldn't recommend getting it.
