The original build came from zayaan's post here, but since he doesn't ever need do this with his 2 kiels, i've put his build to test for the rest of us peasants.
Basically, we can now easily achieve 90% aftercast delay by using Skin of Gwiber +8, and then acquire Fairy Leaf Powder's combo with EA1 and EA2 from other sources, namely our TGL for EA2 and the Temporal Dex boots for EA1. My build has 90% aftercast delay exactly using:
+9 HWHB = 14
New Wave = 10
+9 Medical Scrub = 10
TGL = 20
Skin of Gwiber = 11 (since i have 100 int)
Fairy Leaf powder= 15 (combo with boots and tgl ea1,2)
Blacksmith gloves = 10
Now, obviously my setup isn't the exact same proposed by zayaan (89% using +12 HWHB and 120int/dex). That's because i dont have a +12 hwhb lol, I've sold it some time ago. If you sport a +12 HWHB, you can go for his exact build and end up with 88~89% aftercast delay (depending on whether u have 120int), and then go for a second Fairy Leaf powder instead of blacksmith gloves for 7% more ranged damage. However, if u really want to maximise the dps-theoretically speaking, you will want 90% aftercast and not be able to get 120int because you cant get 190 aspd that way since your agi will be 60-70 maximum. Basically its up to what you like.
I'm personally gonna be removing some of my str to up my agi a bit more so my aspd hits 190 instead of the 188 you see in my video now lol.
SHOUT OUT TO ZAYAAAN!!! (you did me a great service :3)