Erlang Shen vs anybody

The starter item is honestly a must in every game mode as it has become my favorite item and has saved my life (even at levels 15-18) on countless occasions and actually makes you a great pusher with Shang. He's mana intensive early game and this starter items makes you more reliable.

The Qin Sais truly activates Erlang's passive, as it gives you TWO new Damage outputs with each attach (The normal passive of the item, and your dog's passive). Acquiring this item makes everyone become squishy thoughout the entire game on its own. Therefore it's important the next item is defensive, to help with your survivabiity now that your offense is a threat.
If you build stacks with this early game(Armored Cloak), you will be the most annoying thing on the map as you will be hard to kill yet output so much damage (attack speed camp is insane with Qin).
Personally by the time I can get the cloak, my team has advanced and thus I'm covering more ground so I need speed purely for survivalbility and team reliability, thus boots are an obvious choice. (With Erlang's transformation ability, it helps to cover a lot of ground when you have a lot of ground to cover on a retreat, after a tower dive for example so I wait late as possible for boots tbh).
Rage is next as by now your opponents will definitely have built some type of defensive item and if not, rage is still the essence of devastation as its attack speed, Power, and also penetration..
Brawlers Beat stick is to counter every healer, and I've had SO MUCH pleasure destroying other Erlang's who do not use this item to counter my Ult, as I heal all of their damage back but they don't get anything of their own. (If your target cant heal then Ichiaval in theory should be better as its attack speed and also penetration.)
Lastly, Deathbringer is the final key to your passive, awakening critical strikes in your passive. You can try other Crit items but I prefer maximum damage.

Try this build and with some common sense you will be invincible at best or extremely reliable and deadly at worst. Have fun ;)