I've played nearly 100 matches now, and I'm finding that regen, Both HP and mana, seems to be patheticely weak. It is usually to the point where stacking health or mana is a better fix than regen, which seems odd, it feels like it should do something. I'll give some examples though, so you can see for yourself what I mean, maybe you can prove me wrong, maybe you'll agree.
Okay, Clarity runes, the oh so popular mana regen runes. If memory serves, they give 0.1 mp regen per five seconds per level, capping at 1.8 mana regen per five seconds. Notice something there? Per five seconds. At level 1, that means, assuming you have nine of them, with a mana regen of 0.9 per five seconds, that means it'd take 6 seconds to regen 1 mana. At max level, of course, it's 18 times this, yes. It equals out to 16.2 per five, which means 3.24 per second. While that is signifigantly better, it's useless by that point in the game, you will have sucha high cap for mana at that point that the small ticks of regen probably won't even be enough to get you another spell.
We also have the Chalice. Not being able to recall the other stats, it gives 1% extra mana regen per 1% missing. This means you regen 50% faster at 50% mana, a reasonable number to work off of. Seeing that regen example from before though, and looking at items, it isn't a lot. Afterall, the Archangel's staff gives 5 mana per second, and it's the best mana regen item int he game.
To give an HP example, look at the Force of Nature. If I recall correctly, the HP per five bonus is 40, so that'd be 8 HP regen per second. Then the passive itself grants 3.5 HP regen per second per 1000 HP. That's surely not going to save you by the time you can afford it.
The Mastery, Perserverance, grants 4% extra health and mana regen. This means for every 25 regen you have, you get one bonus. This makes it almost useless, because as usual, useless early game, and the effects of negligible late game. Meditation grants 1 mana regen per second, that's not bad at all, surprisingly, considering the other options, because you can have it right away. And the Defense mastery that grants 0.3% of your max mana as health regen, this translates to 3 HP regen per second per 1000 mana.
Oh, and of course, poor Mundo's passive does that, except based off of max health, regenerating less than Force of Nature's passive, which I already went over. His only saving grace for a heal, actually, is his ultimate, his passive is terribly weak.
Anyway, I'm sort of wonder what the point of regen is at all, because it's effects for it's cost are so utterly minimal that it seems almost useless, surely higher health and mana caps are simpler and more effective.