That would do nothing. In the build, WW deals 256x as much damage as Rend, and slapping a 10k multiplier onto Rend is still not enough. Since Rend is a static DOT that can’t crit and doesn’t proc AD or Bloodshed, you would need an additional scaling mechanic to further boost Rend damage–which is exactly what we asked for.
Applying Rend on hit is a bad idea, folks. We really need to put that to bed. It doesn’t do anything to solve our problems, and anyways, auto-casting spenders is bad design. The point of Rend in the set is to gather big clumps of density, then Rend them, and WW through them. There’s an intent behind the design. Now all we need is to get the damage and utility to be worthwhile.