Its self heals. Ones YOU cast like clemency. Its just like Det. Det increases damage you do and heals you cast on a whm. Tenacity does the same thing. Increases your personal damage, increases your outgoing personal heals, but also decreses damage taken. It does all of these things at the same rate (lower damage and heal increase than det). You gear it if you want passive mitigation. The heal bonus is just as strong as the damage it provides, which are both just weaker versions of det.