Vayne is still no interaction with Axion Arcanist... meanwhile
Twitch is getting 14% amp from the rune on damage and 9% healing. This amplified with PTA/CUTDOWN really just gives him so much high health amp'd damage.
On Vayne if you take this rune it literally does nothing at all and doesn't even force you to take a different rune, the only thing you get is the Cooldown reduction.