The equation:
HP regen/sec = [.25 + (STR * .03)] + (hp/sec inrease from skills and items)
Mana Regen: Most heroes have a base of .01 mp/sec. Each additional point of intelligence gives an additional .04 mp/sec. Percent regen increases work off the entire base regen. Example:
A hero with 100 int has a mana regen rate of 4.01 mp/sec [.01 + (100 * .04)]. A void stone will double this. Two void stones will triple it. The equation:
Mana regen/sec = [.01 + (INT * .04)] * (1 + [% increase])
Note: (50% increase => .5, 100% increase => 1, 200% increase => 2, etc)
Hope that helps others. It certainly helps me.
HP Regen: Most heroes have a base of 0.25 hp regeneration per second. Exceptions are:
The morphed form of the Lycanthrope has 3 health per second but only regenerates during the night
The Soul Keeper regenerates 1 health per second in morphed form
The Soul Keeper regenerates 0.5 health per second in normal form but only regenerates during the night
The Shadow Fiend and Ursa Warrior regenerate 0.5 health per second.
This post was made by Epsillon on the Dota-allstars.com forums.