Thats because reserve seal isnt a win condition for water vs lightning. The only possible way reserve seal would fully be maximized is if you have a frontline water main you expect to tank hits. Also, unlike sailor sakura who heals and does an AoE splash standard, you would have to sacrifice standard heal to use the attack boost (unless you really want to just boost chase damage).

With the limited niche use of reserve seal, the alternative talents in that line are just way too good to pass up while you run a lineup with a more solid tank.
Addon:
RoW typically wont succeed vs immortal teams, since they sacrifice offence for defence, and the water doesnt care what defence the opponent is running, she's just DoTing you down with poison. Plus RoW only lasts 2 rounds and in that time you can chip away at the 4th ninja thats not immune.

(I'm assuming that since you're considering reserve seal your lineup is more defensive than offensive)
This post was last edited by Slacker~ at 2017-5-30 09:16

I don't have Reserve Seal unlocked yet tbh (I'm at 73) but I've been struggling to beat a Lightning / Konan / Deathidan / Sailor player and I was wondering if it would be worth it to fight fire with fire (metaphorically) since my usual Neurotoxin build is absolutely helpless against it. The only weak link on the team for me is Konan, and I can't hit remove her before everything has been tagged and gets nuked. This post was last edited by 114***@google at 2017-5-30 09:22

The reason is simple, the other passives on that row are better for our meta teams and actually it's not Neuro, it's mainly the other two, i barely see Neuro used these days.

Multiple healer teams are better with healing tips for obvious reasons.

Mabui/1010/Mei or Mei/Chojuro/Ao or any team that use water ninjas as primary damage dealer are better with water damage boost.

Reserve seal itself is not bad as a passive, it just has no synergy at all with most common water teams because water main is used as support, for reserve seal builds water main has to be move 1 with other ninjas supporting it instead.

Against death hidan, as long as you survive the R1 + R2 first mystery burst, you're golden, his lineup wont be able to win any more once the double heals come out in r2, so adjust your ninjas accordingly to counter this. His sailor isnt going to do anything, you're sailor applies poison at every turn. Identify how you're losing (whether its because of r1 tag, r1 burst, or r2 burst) and see what ninjas you c*e to mitigate this (eg: kabuto clones to soak up tag, gakido for r1 clear, etc).

Reserve seal definately should not be used vs death hidan. Go healing tips.

Reserve seal is an arena talent mostly and works very good with all the 4th row of talents. Sailor sakura, kimimaro, shizune/kabuto with the 4th row of talents is a nice team for arena and can endure root teams. But in most cases neurotoxin is better, that's the problem. This post was last edited by ayr***@yahoo.com at 2017-5-30 16:28

Reserve passive of water main is weaker than sailor's sakura although.. but at this point its better to run something else.

in a sense its not weaker , but on par with sailor's sakura. sure it have less health regeneration but more attack boost to counter this.