One of the first things you may have noticed after your first battle, first death or even your first fall may be that your health is not regenerating despite having a full hunger bar. You may (or may not) be surprised to learn that RLCraft approaches health in a somewhat different way. The First Aid mod comes with an in-game tutorial that it may nag you to go through the first time you load up a world, but it's worth it. This page will cover both topics covered in the First Aid tutorial and additional topics related to the First Aid mod.
Main Article: Locational Damage
RLCraft, thanks to the First Aid mod, has a system called Locational Damage. What this means, first and foremost, is that Skeleton archers are much scarier as they always aim for the head, and a good headshot has the potential to kill. A quality helmet will help save you from some sudden one-shots.
In addition, should specific parts of your body be heavily damaged, you'll incur a debuff, such as Mining Fatigue for arms, or Slowness debuffs for legs and feet.
The critical parts of your body to always make sure to keep healed up are your Head and Body. Bring up your First Aid menu often to make sure these are healed up. If either one of these reaches zero health, you will instantly die, regardless of the health in other parts of your body.
There are a few ways to heal your wounds in RLCraft. In order of easiest to most difficult (and not necessarily by their healing potency), there are:
Nymphs are peaceful creatures that spawn near flowers and give a Regeneration buff, which heals up your health for simply being close to them. The downside is this is a slow process and you need to be very close to the Nymph for the buff to refresh. In addition, as Nymphs are wild, they may eventually leave with no warning, leaving you defenseless and unable to heal. The buff will remain for about three seconds after you leave the Nymph.
Sleeping in a bed will heal you for 50% of your health. This is helpful if you take damage near your home and need to heal up for the next day of rough survival. The drawback to this is, of course, that you can't sleep whenever you want. Other methods are more reliable for long term survival, however this is a good one when you need a quick refresh.
There are various healing items you can craft along with healing items that drop from some mobs later on in your travels.
Plaster can be crafted with string or plant string (obtained by cutting grass with a knife and placing three plant fiber into your crafting menu) and paper, which can be obtained either from two birch wood laid flat into the crafting menu, or three sugarcane laid flat in a crafting table (birch requires a higher crafting level to plant, although sugarcane only grows in the summer [Seasons], so it's worth having a reliable source of both). When rightclicking with the item in the toolbar in hand, the First Aid HUD should pop up. At this point, you should click on the body part in need of healing and hold it down while the timer is counting down. Plaster heals two full hearts to any part of your body that it is applied to.
Bandages can be crafted in the Crafting table by putting any wool in between two string or plant string.
Healing Salve can be crafted using a Dandelion a bowl and any single block flower, and heals a total of 1.5 hearts. The great thing about the Healing salve is that it can be used in the midst of battle.
There is a host of other healing items one can craft or find in the wild. However, their recipes call for more and more demanding ingredients. You may want to look up their recipes by going into your inventory, looking into the item collection on the right and filtering the list for "First Aid". You can view more information on any item by clicking it to view the recipe required.
Many mobs from Lycanites Mobs drop meat that can be used for an instant health effect. Additionally, any vanilla hostile entity (zombies, skeletons, spiders) has a 10% chance to drop either a salve, a plaster or a bandage.
In the mid-late game, or if you're very lucky in relatively early game, regeneration rings, apply regeneration. This is not very fast though, and is more useful for healing minor wounds or healing someone else up after a battle. It is also useful if your armor is very good, so the only damage you do take is almost instantely healed up by the rings. However to craft it you will need a normal potion ring and four ghast tears and a nether star (replace with picture).
You can add to your max health as you progress through the modpack, should you find special crystals and dust. Not only can this dust and crystals be crafted into healing items, but they can also be crafted into Heart Containers. A full 3x3 grid of heart crystals should be enough to craft into a heart container, which should permanently add a new heart to your health bar!