Ravana Nirvana

This won't be an in-depth guide, and it's far from comprehensive, just explaining the concept of the build and you can take it from there and make it your own.

This build is focused on ability damage and sustain, but peppering in basic attack boosters work well too since you should be at least getting the two quick punches in between ability casts. He's good at skirting the edge of a teamfight, or quick in and outs to dump your kit, and doesn't have to return to fountain as much, just self-heal off a row of minions. I use my ult to chase 2+ low health enemies, to initiate 2nd (after another teammate initiates, if the enemies group together), and sometimes as an escape since it makes you cc immune (the CD isn't that bad, and it doesn't feel like a waste since your just utilizing it defensively for the leap and mitigations).

Core:

Heartseeker for extra ability damage since this is a lower power build.

Spirit Robe for protections and damage mitigation when cc'd, which is inevitable. You can also use Mantle of Discord, but if you do I would get some CCR elsewhere.

Arondight for your primary source of power, and a little buff when you ult. Transcendence also works if you have a few other mana items, otherwise the Arondight passive will usually beat it out. I wouldn't recommend Devourers or Bloodforge, the lifesteal isn't going to do much for you.

Very optional: Soul Eater works really well for this build but it's hard to work in without sacrificing something else. Healing from all of your abilities really helps with sustain and especially escapes when your health is low and you 2 is on cd. Definitely more useful on higher damage variations of this build, or with Caduceus in combination with a teammate with Rod of Asclepius.

This build was theorycrafted and tested in Arena, but I'm confident it would do well in any game mode. Conquest might require switching up the order, but I feel mp5 is always super valuable at the start of all modes, especially when you have a self heal, and especially when you have a self heal, a root, cc immunity, and a slow.

His whole kit can be used offensively or defensively, and he plays best when you're also using basic attacks between casts. I've done my best here to build around that to make full use of his kit.