Dark Souls 2 has made some tweaks to the healing mechanics of the original, introducing lifegems as well as the traditional Estus Flasks.
It’s important to understand the distinction between the two, especially in the early part of the game, where you lack sufficient Estus Flasks to last very long.
Estus Flasks work in much the same way as they did in Dark Souls. The key difference is that you have to earn more flasks by discovering additional Estus Flask Shards hidden throughout the world. The first shard is found in Majula, check out our guide to find out where it is.
Estus Flask Shards must be taken to the Emerald Herald in Majula in order to obtain a new Estus Flask. Sublime Bone Dust can also be thrown into the Majula bonfire to improve the amount of health you get back from your Estus Flasks.
Estus Flasks recover a large amount of health in a short amount of time, but you cannot move while drinking the potion. If you press the action button while your character is drinking, it allows for multiple uses without putting the bottle down, saving potentially vital seconds.Your flasks replenish when you rest or respawn at a bonfire, unlike lifegems.
After your first death, your character will ‘hollow’. Each time you die, your maximum amount of health will be cut. Using a Human Effigy will reverse hollowing, and remove any effects to your health bar.
Burning an Effigy also prevents other players from invading your world for an hour. Human Effigies can be found throughout Drangleic, but can also be bought from some merchants.
Lifegems are health pickups which can be found in chests or corpses while exploring Drangleic. Unlike flasks, they do not replenish at bonfires, they are one-use items. One benefit they do have over flasks is that you can continue to move while using them, and they are also quicker to use. The downside is your health takes longer to regenerate with a lifegem.
Lifegems are better to use against bosses, as you can continue to move away from the fray while healing, plus you don’t have to wait long before bringing your shield back up or fleeing from danger.
Lifegems are available in different sizes and forms, affecting how quickly and how much life they restore.
Dark Souls 2 Beginner’s Guide - Estus Flasks and Lifegems