Pretty sure there’s a display bug once your character reaches 1,000,000 HP. The Stats screen displays that you have 1 HP.
(EDIT: Btw, I achieved this by allocating all 294 points into my warrior’s health, having +20,000 HP from gear, another +50% HP from gear, Vampiric Touch (5) for +62.5% HP, Faun’s Gifts (5) for +62.5% of my 750% Luck as HP, and Plagued (5) on Stitch pet for another +125% HP.)
I know it’s a display bug (i.e. my character does not actually have just 1 HP) because enemy attacks do move my health bar a little bit; I’m not one-shotted like 100% glasscannon. I can also verify that when I respec my stat points and start adding health points back in, the display starts showing things like “1.11101E+06”
I can post screenshots if it’s necessary, but that seems like a lot of work. Just thought I’d post a bug report for someone to check it out.