What Is Regen In %?

So what is regen in percentages? This is a question I've been wondering for a bit, I heard some places it changed your totem timer so if you have 100% hp regen instead of getting a certain number of hp in 4 seconds you get the same amount in 2 seconds with 100% HP regen. Or is it just increasing the amount of regen you have in percentages but the timer still stays 4 seconds?

 

these are all interesting viewpoints.

regen in % just changes your regen raw.
for example, if you have 1000 health regen raw, and you have 70% health regen on top of that, then that 1000 hpr is going to turn into 1700.

if you don't have any raw regen, the regen % will do nothing.