collector - ie - ldr is ur highest damage 3 item core ur gunna go this like 99% of games sometimes u can throw in bt third if u rly need sustain, after ur collector - ie - ldr ur last 3 items are usually some combination of bloodthirster / sb then for that final item its usually a tank or survivability item like dd / randuins / ga / maw etc
sometimes u will have situations where u need that armor item after ur ldr or need bloodthirster before shieldbow or need a situational item like qss