I do not know whether mei is worth 13k, because the worth of the ninja depends solely on you. That being said I can tell you what is good and bad about Mei so you can make your own choice :
(Keep in mind she is attainable in Seal Treasure too, so you may get her for free with luck)
Mystery :
Overall, Mei is a very decent ninja. Her mystery attack costs 60 chakra, has 1 turn battle cooldown, and can be used again after 2 rounds. Mystery will attack 7 opponents, and ignite all the targets (which is very good) also low float on the main target.
Damage from the mystery is decentish, nothing game changing, but not weak either.
Standard :
Standard attack is both Tai and Nin, damage is decent, and will cause acupuncture if she does 3 hits.
Chase :
Chases knockdown, causes low float and immobilize - awesome chase. (not very damaging, but I do not think it matters that much in this case)
Passives :
1. Mei deals 25% increased damage to male characters. I haven't really noticed it in combat, but incresed damage is always good.
2. Zone... And that's probably the only thing where I do not know what to think of her.
Auto zone (so you will only have it if you have higher initiative, only for 3 rounds and can't be re-cast) gives buff of 40% to 9 fire or water ninjas in your entire team, and befoe first action Mei takes in the round when the zone is active, will poison two enemies dealing okayish damage (like half her standard)
Mei is great in : Ranked combat, Very short 1v1 battles, 9tails. But definitely less good in : Long 1v1 fights, world bosses lasting more than 3 rounds. GNW is somewhere in between these two, very much depends on your opponents.
Enemies with higher initiative, having normal zone casters, or genjutsu mirror thingy are annoying to deal with. This post was last edited by TakafumiNaito at 2017-3-16 19:02