-Phantom dancer can be swapped for shiv as first item as it is down to preference, but phantom dancer can be taken when you want to 1v1 / 2v2 in lane to get ahead

-100% crit is not completely vital but is nice, Essence Reaver can be swapped for a multitude of items depending on the game situation (lord dominiks, mercurial scimtar, maw etc.)

-The build order after the first 2 items is also very flexible depending on the situation each game

-The reason for including essence reaver is that it makes the build reach 100% crit chance, but mainly the 30% CDR it gives. This ensures that your tumble refreshed noticeably quicker than other builds, making Vayne even more mobile, making repositioning easier, and most importantly making her much harder to lock down for your enemies

-An armour pen item is not always necessary for two reasons : with the new meta there are generally more squishy teams overall, and vaynes W means she cuts through tanks extremely fast regardless of an armour pen item