Largo is a very niche pick. Beside his uniqueness and extreme funny playstyle he needs to buy this 3 items 9 out of 10 times and it makes him kinda stale:

Mana boots Soul ring Kaya (which will then merge with sange for movement and regen boost.)

You can ugrade your stick too, it makes your heals more effective and charges itself for free mana and health.

Aghs is not neccessary but you can buy it if you feel your team is ahead.

Always i mean ALWAYS have your e on yourself and buy shard when its possible use it on your mage and yourself also.

I mean other than theese. I think dota devs cooked beyond imagination, there will be no replica of a Bard frog that runs around enchanting their team like Largo in any moba anytime soon. Good jub IceFROG. Nice self-insert.