Currently on the PBE:
Chain Lash (Q)
First hit damage AP ratio increased from 60% to 70%
damage increased from 60/90/120/150/180 to 60/100/40/180/220
healing increased from 50/80/110/140/170 to 60/80/100/120/140
heal AP ratio increased from 35% to 45%
After playing against him some more it looks to me like his heal might be a little too powerful. For reference, Vlad's targeted heal can heal him for 20 / 25 / 30 / 35 / 40 (+ 35% AP). At rank 9, Vlad can heal for about the same as Sylas does with Crimson Rush. This doesn't take into account the fact that Sylas has his heal doubled when below 40% health which means he currently can get a 340 + 70%AP heal at rank 9 and at rank 1 it's 100 + 60%AP. Of course you can't directly compare the two because Vlad is ranged, has an easier time procing it, etc. However, considering Sylas' heal is also targeted with a hefty amount of damage as well as the fact that he doesn't really have all that much trouble getting to a target (especially in the early game) it is a pretty insane heal.
His heal can make him insanely hard to push out of lane because of how easy it is to proc and makes his all ins super crazy as well. Doesn't really feel fun playing against someone who can win a trade or all in because he used his targeted heal. I would consider lowering the base by a lot more and increasing the AP Ratio more to compensate. Another option could be to make the threshold for the double heal a lot lower (20 - 30%). He's already in a solid spot for a new champion so I'm kinda confused as to why he is even being buffed in the first place tbh.