Healing: An Unhealthy Mechanic
Many players, especially those playing clerics, turn to healing their teammates as a method of support, as healing is a classic archetype in media and a seemingly obvious way of supporting allies, keeping them further from unconsciousness. However, DnD 5e heavily disincentives this method of support in multiple ways, leading to it being a poor choice in nearly all cases.
Problem 1: Health Doesn’t Matter
In D&D 5e, your effectiveness does not change until you hit 0hp. Due to this, spending actions to raise someone’s health while they’re at half health, for example, is no different to spending actions to raise someone’s health once they hit 0hp. They’ll immediately become conscious again, just as functional as if they’d never gone down at all. There’s no reason to pre-emptively “top up” someone’s health, as it provides no benefit over just waiting for them to go down to heal them then. This means that healing is not needed frequently enough to warrant dedicating a whole player to it, and anyone can just pick up Healing Word and provide all the healing you need.
Problem 2: Healing Spells Don’t Provide Enough Value
The second main problem with healing is that all combat-relevant healing spells provide far too little healing to properly counteract the high damage dealt by monsters, and therefore won’t reasonably keep an ally conscious much longer and aren’t worth spending slots on. You can provide far more value by spending those same slots to eliminate enemies from the fight and prevent that damage from being taken in the first place.
The Hope: When Healing Is Useful
There are, however, two ways to provide useful healing. Neither are major enough roles to dedicate a whole character to, but they are things to keep in mind. The first, as touched on earlier, is so-called “yo-yo healing”. This is using cheap healing to bring an ally back up from 0hp, allowing them to fully contribute to the action economy for low cost. A prime candidate for this is Healing Word, as its bonus action cost is easy to fit into your turns, and a single level 1 spell slot is a small price to pay. There’s no need to upcast it for this purpose, as the minute scaling won’t measurably change how fast the ally goes back down. The other valid use of healing is high slot value out of combat healing. Two prime examples of this are Goodberry and Aura of Vitality. Both provide large amounts of healing for the slot cost, and can easily be used during breaks after combat. You can also cast Goodberry using leftover slots before a long rest, and save the berries for the next day.