I think spell vamp was removed too early and here is why
So as we all know Spell Vamp was recently removed from League of Legends. Now I'm sure a lot of you are asking "so what? Who cares?" and that is exactly why I think it was removed too early.
I haven't been able to track down a straight out reason as to why Riot decided to remove spell vamp but let me ask you a question. What was the purpose of spell vamp in the first place? Also a mystery as I can't track down an exact quote from a rioter, but let me try to reason it out for you.
Mages are known for be able to do lots of damage to both single targets and entire teams. To balance this out, they are, generally speaking, squishy and easy to kill. Sound familar? Don't ADC's fill this same category? Their only differences being how they deliver damage and the type of damage applied.
Because life steal exist in this game to give ADC's some pseudo-tankiness and mages are, structurally, similar to adc's I can only assume that spell vamp was added to give mages some pseudo-tankiness as well, or help them sustain in lane.
But if that is true, then why is spellvamp being removed but lifesteal isn't? I think that it is a matter of popularity. Lifesteal isn't build on everyone but it is a really good stat for those ADC's that do build it, mostly being built on ADC's that get a high attack speed. For these ADC's, there are viable items that grant either a good amount of damage or attack speed plus a good chunk of lifesteal.
QUICK NAME ME TWO LIFESTEAL ITEMS!!
you probably guessed
and
Both of these items are pretty good on adc's.
Bloodthirster sports a whopping 20% lifesteal, plus 75 damage (the most AD you can get from a single item) and the shield is really great at negating poke damage in lane or before teamfights.
Bork gives you small damage, 40% attack speed, 10% lifesteal, 6% of the targets health in magic damage on hit, plus an active that can be used to escape OR catch a target out.
QUICK, NAME ME TWO SPELLVAMP ITEMS!!!
you probably named Will of the ancients and hextech gunblade
Will of the ancients gave you a decent amount of AP (80 ap to be exact) and used to give you 20% spell vamp but this was reduced to 15% of all damage dealt would heal you, and also 10% CDR.
Do you see the problem with this? Sure it gives AP,CDR, and spellvamp, but since all of our CDR needs are met by
, paying for more cdr feels like a waste. And it's not like we can just replace nomicon with WOTA because finding the extra 10% cdr needed to max our cdr was...really difficult and felt awkward. Considering that there was no usefull active or extremely useful special passive means that this slot is better suited for a Zhonya's or later, a ludens echo. It just wasn't a good item.
and gunblade made you spend a lot of money on AD stats that no one would need unless they were a hybrid build.
And instead of properly tweaking items or providing some actual viable spell vamp items they just said "fuck it" and just took the whole thing out altogether. I feel like Riot didn't give spell vamp a proper chance or even put any effort into expressing this cool stat.
tl;dr Riot never tried to make spellvamp a viable option, and because it wasn't a viable option, they removed it
and partially because of this girl 


Using mana returns 20% of the cost into hp up 15 per spell. This is the pseudo sustain item that replaced WoTA. More people use Catalyst based items (
) than WotA. Sure, it isn't much. It isn't meant to be!
<--- This guy ulting with a ROA is why it cannot be allowed to be much. But it allows mages to trade back some. Get hit? Get some mana to fight back. Used mana? Get some heal. See the repeat?
This works in a similar fashion. Mana and HP regen depending on current values.
...that built tank.