Low levels of Survivor's Instinct are handy when you return to town to sell loot, etc., but not that useful while exploring/fighting. A maxed Survivor's Instinct regains 1 hit point every 4 seconds. For a bonus;
Level 5: Regenerate vitality at a rate of 4
bonus 1: Regenerate vitality at a rate of 2
bonus 2: Regenerate vitality at a rate of 1
bonus 3: Regenerate vitality at a rate of 0.5
bonus 4: Regenerate vitality at a rate of 0.25
