UNFAIR INCONSISTENCY: Heal Power vs. Drain Effects

EDIT: Death's Dance contaminated the lifesteal test. I tested again and lifesteal is not increaesed as I previously stated. Lifesteal and Spell vamp are both not affected, but the omnivamp remains exceptional.

Heal Power increases https://vignette.wikia.nocookie.net/leagueoflegends/images/2/24/Ravenous_Hunter_rune.png/revision/latest/scale-to-width-down/64?cb=20171027170107 omnivamp, but it doesn't increase Lifesteal or Spell Vamp.

https://imgur.com/gallery/8eFVP

While I use the term 'Drain effects' (used to be on Spirit Visage): do not confuse it with the Drain ability. All healing from your own abilities (that I've tested for far) count as 'Heals' (i.e. are improved by Heal Power), even if the amount healed is based on damage dealt (before or after resistances). Drain, Determination, Jaws of the Beast, etc, all get buffed. It's literally just healing from the Spell Vamp statistic that isn't improved.