On the topic of Lifegiver, specifically the Regrowth and Mana Regen upgrades. I searched and found several threads stating that Lifegiver is underpowered, that Regrowth isn't worth it, etc. I know what these skills SAY they do, by their description. But my question is, do these two upgrades actually do ANYTHING at all?

I have the option ticked to show my HP and Mana percentages. I have taken all upgrades for Lifegiver. When I cast charged Lifegiver, I can see +HP and +Mana numbers popping out above my head. But the percentages in the HP and Mana bar do not appear to be increasing any more quickly than if I just stand still and let them naturally regen. Do these two upgrades actually do anything? Do they only work for others and not on the mage casting them? If your answer is yes, of course they work, how can you tell they're working?