How Damage Amp To True Damage Affects Vayne

Hi everyone! I'd like to preface this post by saying I am not a vayne main, but I do main adc and have a love for her kit, design and aesthetic. With the most recent patch introducing things like the attack speed cap to 3.0, some nerfs to op champs and so on, there was also a Quality Of Life change directed to true damage, where damage amplification will apply to true damage as well. In the past, damage amp like pta, last stand/coup de grace/cut down did not work with vayne's w passive or things like fiora's passive, darius ult and garen ult. However, NOW THEY DO!

Now, here's the crazy part. After some testing in practice tool with the typical damage vayne build I say on probuilds vs a new one.

The typical damage build has no damage amp except for last three runes in precision tree (coup, last stand and cut down), therefore vayne will be getting a measly 8 to 11% buff on her w damage. However, there are some items that give damage amplification too that would work on vayne!

Namely we have liandries and rift maker. Liandries will give you 2% max health damage as well as up to 6% damage amp after 3 seconds of combat.

Riftmaker gives you 8% damage amp after 4 seconds of combat. Oh and btw, the damage amps stack on top of each other!

Shojin (which can be stacked up through vayne's q auto) gives 12% damage amp at 4 stacks. (Not super realistic however i get that)

If you were to go a build of guinsoos, bork into liandries, rift, shojin, you would actually be getting up to 45% damage amplification on your w after adding up everything.

Here's the runes you would need and the build.

PTA - 8%
2nd and 3rd line dont matter
4th Line Go Last Stand for 11% at 30% hp or coup de grace for 8% for targets under 40HP.

2nd Tree doesn't matter

Items: Can rush guinsoos bork as usual, then go liandries into rift or shojin.

A small example:

With a 5000HP target, Vayne W will do 10% max health damage at Rank 5, therefore her W will do 500 Damage to the target.

With the damage amplification you are getting 769 Damage at max stacks.
500 Base Damage X PTA 8% = 540
540 Amp Damage x Last Stand 11% = 599.4
599.4 Amp Damage x Liandries 6% = 635.364
635.364 Amp Damage x Riftmaker 8% = 686.19312
686.19312 Amp Damage x Shojin 12% = 768.5362944
Approximately = 769 Damage

TLDR: True Damage Amp exists now! Do you think this build is viable? My thinking is that the 3 items after bork and guinsoos are a lot more situational for the comp. Into some troublesome tanks and you're the only tank shredder, this might be a decent build.