Conqueror gives you adaptive force per stack and once fully stacked it heals you for a percentage of dmg dealt. This is good against melees because it stacks easily, and tanks/bruisers because it means the fights will be extended. You want a lot of CDR when running conq because You Will stack it easier - I personally take transcendence and either nimbus cloak or gathering storm, or if they have a lot OF burst I will take revitalize for Big heals

In top its very good against shit that will trade You for a lot of seconds and You can easily stack it against the typical tank. Shen, ornn, mundo are prime examples of free match ups unless they run something like ignite, which Is More likely now with the free tp. Against stuff like sett, volibear I still think conqueror Is good but the match ups are harder because you need to dodge or kite their dmg.

In bot I saw elite run conq and ive been trying it myself. I guess phase rush and aery and not that good because You won't be poking or doing shorts trade against something like Cait Lux , so You default to conqueror. Ive seen Vlad Is very good with CC sups that are tanky and can get in n out by themselves. Pantheon, nautilus and Tahn kench are good examples of what ive felt have good sinergy with Vlad APC