Reserve 95% or more of your Life. (Reserves 30% of Life, Search)
Reservation is a method of using a resource, typically mana or life, to pay for auras, herald skills, buffs, mine skills, or any skill with an ongoing effect. Some items may also reserve resources. Rather than paying the cost once as with normal skills, a portion of the resource is set aside as unusable for as long as the skill is active. Reserving a resource does not affect its maximum, so percentage modifiers such as Regenerate 1% of Maximum Life are unaffected when you reserve life, for example.
Reserved resource values from Skills are multiplied by support gem cost & reservation multipliers as usual. The Blood Magic Keystone and Arrogance Support will cause skills that usually reserve Mana to reserve Life instead.
By default, all gems reserve mana instead of life. No skill gems reserve life, however life can be reserved using the following methods: