Dwarf skill

[Rimolan]

Hi . I come with interesting question. I need deeper information about skill  "tenacity". I want to know if  it is fixed amount of hp back, if it depend (% of) max charecter HP, if is affected by any rune(like heal power) and how offten it trigger, also if 3 targets atack me it will trigger x3 of usual time or no....just some deep info becouse cant find any tests, labs or offi info for it.