This is an Umbral [Nezha] built around getting a bunch of armor from his 3rd when cast, but with this build all of his abilities are good. With this current Build, His ring will have 2223 health(Unboosted by absorbing damage) and 4200 Armor. Have Fun being Immortal Tenno

If you wanted to be even tankier, you could use the helminth system to replace his 1st or 4th. While this is not necessarily Tanky, Adding Fire Blast will look cool with his kit as well as having good bonuses. This will strip enemy armor as well as CC them from the Fire Procs. This turns into more survivability since enemies are flailing their arms around and not shooting at you. Defy from [Wukong] is also an Option. It is likely not the best since your duration is not very high, but if you get near a large group of enemies it will not be very hard to get the 750 extra Armor.