While playing Vlad today, I noticed "Tides of Blood" doesn't proc spell vamp. The ability does magic damage; why doesn't it absorb health?
Edit:
I was playing a bot game with around 600 AP, a Spirit Visage, and a Will of the Ancients. I used Tides of Blood while surrounded by 10+ minions and noticed no spell vamp. Magic dmg should have been ~450 to each minion, so 450 * (.25*.33) = ~37, not counting spirit visage.
It's possible I just didn't do enough damage to trigger the floating text, but I started watching my health bar to see. It's difficult to tell since Tides of Blood damages Vlad when cast, but I still should have been gaining 300+ health.
UPDATE
It was late when I posted this, and I must have made a mistake. I was able to confirm last night that Tides of Blood does proc spell vamp.
Side note, I often noticed only 1 green number pop when I got high enough. It seems they've combined the floating text into one number, making it easier to see how much health he gets back!
Best Answer
It should work, but probably you cannot see it because the numbers are too low to break the threshold for spell vamp visual effect. More details on this forum discussion.