I was thinking a flat health on hit item belongs in the game.

Similar to the way malady does magic damage on hit, an item that heals for a flat amount instead of percentage based like life steal does.

I think it would add build diversity to the game for characters that need some sustain but build attack speed instead of damage.

As long as its balanced correctly vs life steal I cant see why not.

I once proposed this:

Flintlock Sword
PASSIVE UNIQUE: On hit, you replenish 15 health and 9 mana.
Recipe: Catalyst the Protector and Pickaxe
Stats: +40 attack damage, +300 health, +325 mana

But I agree, it would be nice to see a sustain option for attack speed builds. I think Blade of the Ruined King might become this, though (4% of their maximum health as damage; and healing for half that).

I'd not like this. ADCs are supposed to be very weak in the early part of the game with little to no regen. The early is meant to trade directly with the late and then they have their moment to shine. If you meant these on a bruiser then normally they have some way to sustain or great dmg so they don't need it as much as their opponent. If you wan't this for AS builds, and you attack for 2.5 AS, then you could get crazy sustain in the lane, but you would also push it hardcore. I'm not sure, I just really don't like the idea overall. I feel like AD items shouldnt pack much sustain other than life steal.

There are so many champs that would break this item. Cho'gath, Jayce, Nasus, Gp, Yorick, the list goes on.

Apparently, there are rumors that Xypherous might change all low-tier Lifesteal into a flat heal instead of a %.

That list would include Xin Zhao.... He would be the most annoying thing every with such an item.

This would just a matter of stat tweaking and balance.

Lets examine; Right now with a vampiric scepter you 10% life steal. the average damage on a lv 6 character without items is 70. So 7hp per hit healed. Add a BFS your at 11hp healed or another scepter would give you 14hp. Its critical hit that really lets AD champions shine with life steal.

So the options there for them and scales into the late game. thats ADCs advantage with life steal items. Flat life steal would only benefit champions who prioritize AS as a stat. They could still build % life steal I guess.

I started to comment on the implications of synergy with Shen and his Q (dear god, you think he's hard to kill now..)

But then I realized even more frightfully that this would be a Teemo buff.
ಠ_ಠ

You know we're already experimenting with alternate sustain mechanics like Blade of the Ruined King - which is effectively a form of life steal that doesn't really care about how much damage you have (only have much Penetration you have and the target's health.)

Life on Hit will most likely find its way onto Doran's Blade to get rid of items with small amounts of Life Steal from being rampant. Other small %'s of Life Steal from masteries and runes will probably stay where it is. This has the effect of cancelling a little bit of the Doran's Blade snowball from crits - but also ensure that the Bruiser stacking Doran's Blade to snowball out will also get a bit of reverse snowball as the item doesn't scale into late game.

9 mana per hit is pretty insane when you think about it, most skills cost ~50 mana, with ultimates costing around ~100 mana. So, with ~6 hits you could get back the cost of regular skills, and in around ~11 you'd get a free-cost ultimate. Essentially, you'd have no need for a mana bar in the first place if you utilize auto-attacks regularly. Another way to look at it would be 45 mana regeneration per 5 on every hit, which is a little insane as well. The Attributes seem niche enough to keep most auto-attackers from this though, I'd imagine with the Catalyst this would become something more like another Manamune. I could see potentially getting it on someone like Diana though.

Sounds cool, can't wait to see what you've worked on for season 3

Blade of the Ruined King is already one of my favorite items, I really like picking that up