Just a simple fun run with Exdeath friend in the background while Vayne repeatedly take turns without having to worry about the orb because the HP sap from Exdeath BT will keep the orb at max.
The ideal situation was to take full advantage of Vayne follow-up getting BRV from hitting all 3 targets while Caius BT, but it appeared that the adds died way too fast with a BT finisher, Exdeath BT HP sap and Caius splash in the process. Otherwise this run would have gone much faster.
The most difficult part is the start of the battle. The use of Vayne's LD or Ex have to be caluclated before you hit the button because the number of consecutive turns that followed / the space that the boss get pushed off from breaks may result in the orb not having time to be maintained. That being said, the orb can go as far down as 1 when the boss turn comes and it would tick up immediately after its turn taking into account of the -2 from its turn.
Yda, by design, is here to take out the adds after their first turn and get as much damage out as possible before Exdeath comes. Therefore there was a volatile use of her LD just to quickly destroy the adds so the boss could summon a second wave for Vayne to take advantage of.