Your turrets get part of you stats so you want to make them tankier You will most likely not have 3 flex slots for purple so just go for next items or upgrades Your 2 works on your turrets for extra regen and atack speed.
Soul Rebirth gives you more CD % so you can spam more Turrets Echo Shard for extra turrets Heroic Aura actually gives you atack speed for your turrets as well and you can combo with 2.
This is a Build focused on Turrets. Early game we focus on surviving and farming souls and lategame we have a lot of turrets that slow the enemy and do insane amount of damage.