League of Legends (LoL) Question: % Health Runes

I don't see them being that worth compared to other Runes. They are effective in case having like 3500+ hit points and therefore using health Runes is safer in literally all stages of the game. Greater Seal of Scaling Health/ Greater Seal of Health (or Greater Seal of Armor) are optimal. Greater Quintessence of Armor outshines Greater Quintessence of Health and therefore you can combine it with health seals.

They can be beastly late game with the right kit (% damage based on your health), but you have to make it to late game. Example - ran a Nautilus build (5.5 patch) with scaling health and % Health Quints just to see how it would work. My early jungle clears were atrocious and my gank pressure nil due to being low on health and having no movement speed quints to get places in a reasonable amount of time (Nautilus is slooooooow). By mid-game I started to scale up and later in the game I was nigh unkillable, but too bad the enemy team's laners were quite fat due to the ganks their jungler was able to pull off while I was busy trying to survive in the jungle and scale up.

For the most part, scale with items. Let your runes and masteries help you in the early game when you don't have any items.

Actually there is extremely rare situations they are viable - and yet, they don't make such great difference from runes of scaling health. In theory, to be viable %hp runes must outscale hp/level runes. Mathematic part:

Greater Seals
0,5%=23,94 | x200
100%=4788
So for yellow runes to be more viable you need to get more than 4788 health points with full build. Apart from consideration of probability you'll reach full build is ~10% for game, and you're reaching 18 level in far more frequenstly.

Greater Quintessences
1,5%=48,6 | x200
300%=9720 | /3
100%=3240

In Quints case it's more viable. If you play as natural high hp champion ( Cho'Gath) or your champion highly benefit from health like Volibear those runes may be not bad idea.

They aren't very useful most of the time. If you have an insane amount of HP (like, 4000+), they're good, but this is rare. The quints, that is. The seals are literally useless.

i run them on full tank fiddlesticks. It's so gamebreaking they ban it out against me every inhouse, so basically theyre only viable on fiddle