First Topic: Healing in 5e!
Healing is... bad, in 5e.
Compared to other TTRPGs, MMOs, or tactical board games, healing in 5e is a pretty bad deal.
Particularly in combat, particularly from spells. Cure wounds is not a good spell. Artificers and rangers often want it for lack of other options, but when you cast cure wounds, you are usually spending your action plus a resource to heal less damage than one monster can deal in one of their two attacks.
What makes healing in combat good, is that in 5e, dying is also bad (as in, it's hard to die). A character can spend a lot of time bleeding out at 0 in 5e before they die-die. And if you're healing a character at 0, you aren't just staving off the next half-an-attack they'd take, you're giving them a full turn to act again.
This is why healing word is so much better. Instead of trading your action—most of your turn—to give your downed friend the chance to act again, you're only giving up your bonus action. Plus it has a 60-foot range compared to cure wounds' touch!
The only edge cure wounds has over healing word, is if the average 2 points of extra healing from cure keeps them up through an attack that would otherwise down them (a d4 vs. a d8 is a very minimal difference, at the end of the day).
This is why, in combat, you should be looking to prioritize a lot of small heals, riding the brink of death. Bulk healing in combat isn't usually viable, cure wounds is a terrible upcast. Jumping from 1st to 3rd only adds an average of 9 extra healing, and is almost never worth it.
Get more comfortable riding along at 20% or fewer hit points. You don't need to be topped up for every fight! Like I said, dying in 5e is hard.
That being said, here are a handful of in-combat bulk heal options that are more viable:
-the heal spell. It's 6th level, but 70 hit points is a big enough chunk to be worth it.
-the life transference spell, 3rd level. Sure it hurts the caster, but it's probably the lowest level bulk heal that's actually good. It heals approximately double of what an equivalent level cure wounds does. It also has a 30-foot range! Oh, and did I mention that wizards can cast it?
-high level potions: superior and supreme potions of healing actually heal a big enough bulk that they'll let people tanks some hits. Greaters and basics are best used to pick someone up, or, if you really need it or have a lot of them, out of combat, or when you don't have anything else to do with that action economy.
-certain class features, like the peace cleric's balm of peace, or a big chunk of the paladin's lay on hands (though lay on hands is often better served just spending one point at a time to pick people up from 0).
~-~-~
Out of Combat:
Is a different story. There's quite a few options that are much better at topping people up when you're not worried about enemies slicing you in half.
Certain spells, such as healing spirit, aura of vitality, and prayer of healing are massive upgrades over just pumping out spell slots on cure wounds. When outside combat, healing spirit might be the best spell in the game to upcast for healing, as it adds a number of d6s equal to your spellcasting modifier + 1 for every level you upcast it (so 6d6 if you have a 20 in your casting stat).
But the absolute king of out of combat healing is the short rest. Every day you manage to spend hit dice instead of spell slots or potions is a victory. Go for this options first, if you think it's safe to do so.
There's also the Healer feat and temp HP, both of which I cover farther down.
~-~-~
Making & Playing a Healer:
Firstly, the healer archetype isn't needed in 5e. What is needed, is a couple party members who can healing word up downed party members in a fight. You don't need a dedicated healer.
Second, Clerics are Bad Healers in 5e.
Giving that it's own line.
The best healers in 5e get class features that they can use to heal people without spending their spell slots. Only two and a half clerics subclasses get this. (Life and Peace, with an honorable mention for Grave. Of the three, the only one that makes a truly good healer is the Peace domain.)
The celestial warlock, circle of dreams druid, peace cleric, and paladins (though they're hampered by their lack of healing word) are frontrunners for healing utility because they have great healing options while not needing to sacrifice their other resources.
The next tier of healers are the ones that get abilities that augment their heals, stretching them out farther: the grave and life clerics, stars druid, alchemist artificer, and divine soul sorcerer (have you ever twinned the heal spell? Feels fantastic). Honorable mention to lore bard and any druid for access to spells like healing spirit and aura of vitality, alongside healing word.
Although my biggest suggestion, if you want to make a healer, is to take the Healer Feat.
This thing stretches out your healing massively. For each creature, you can heal for their level + 4 + 1d6, for no resources. And if they take a short rest, you can do it again! If your 6 person party gets one short rest in, at 6th level, that's 162 points of healing for zero spell slots. It can also be used in combat in a pinch, and shoutout to the thief rogue for being able to use it as a bonus action!
~-~-~
One last honorable mention goes to temporary hit points. When you're not trying to bring people up from 0, temp HP is just as good as healing. For that reason, the Inspiring Leader feat is excellent, and if you pair it with the Healer feat on any character you've made a very potent support build that can easily give your party hundreds of extra hit points each adventuring day. Other good options for temp HP include: the twilight cleric (easily the best one), the glamour bard, artillerist artificer (using the protector cannon), alchemist artificer, and the celestial warlock—back again!
Nathaniel Kreiman (they/he) is a pro GM, disability consultant, and TTRPG Designer (Flee, Mortals!, Vineyard RPG.) If you’d like to check out Nat’s work or play a game with them, here’s their links!