Sustain NEEDS to be de-emphasized on Vlad.

His Q should function to alleviate the costs of his W and E, not function as high sustain over that unless you invest into it, like Zac's blobs. Most people think he's all about sustain when WotA's what does most of the healing on him before late game. That's how little the heal actually does for him, yet people hold it as a part of his identity, and that holds him back.

That's where you start making him healthier. Abilities that have costs based on current health. Q that sustains based on missing health. His 'sweet-spot' that he can maintain indefinitely should be somewhere between 70% and 85% of his max HP.

Take away the heal ratio, leave the flat heal (to act as a bonus after he eventually leaves lane), but attach it to anything besides Q.

After that, do whatever you need to do to make him more interesting, such as increased W size based on current HP, similar to Zac's hidden passive scaling, or changing his E, which has loads of room to add some counterplay and more interesting building mechanic than a flat boost for each stack he gets when he uses it.

Just keep his short-ranged, DPS nature, along with his passive bonus HP and W that allow him to function as such.

I'd suggest changing his ult too. Vlad's kit will inherently be weak if he has such a powerful teamfight tool that doesn't even mesh with his kit that well. It stops you from casting Q or E for a second, ffs. His kit will always be left weak if he keeps such a game-changer that isn't even very reliant on his own follow-up.

Give him an ult that fits the theme of blood-mage in line with his kit a bit more. Think emphasizing his passive or changed E. Think Jax ult/passive interaction, or Ryze ult/passive interaction. Think inverse Trundle Ult. Steal the offensive stats of your opponent to empower yourself. Blood magic is a sacrificial, thieving, selfish magic. Use an ult that emphasizes that through the passive or by itself.