So there's one thing I really dislike about 5e - and that's the whack-a-mole effect. I've spoken about it briefly before (in my article on injuries & setbacks, which incidentally is part of the fix for making games like 5e "grittier" and more dangerous), but for now I want to suggest a very quick and easy fix.
Whack-a-mole is the result of a few related matters: (i) bonus action, (ii) ranged healing (healing word etc), (iii) there being no penalties for being reduced to zero hp (in fact - sadly - there is an incentive to drop below zero THEN heal - because you dont track negative HP, you are sometimes better off dropping first, then healing), and (iv) healing magic is instantaneous.
You can tweak a number of these factors to discourage whack-a-mole to a greater or lesser extent. Remove ranged healing (touch only). Make it a full action. Count negative HPs. Or make dropping to zero a very serious and incapacitating condition - like the old 2e rules, once you dropped to zero, you couldn't fight or cast spells for 24 hours (or something like that, I forget exactly). This last option gives dropping to zero the dread it deserves, but is imo too severe in practice (unless you're going for a very gritty style, and dont mind your party camping for extended recovery periods).
So what's the easy fix I had in mind?
It's tweaking the "instant" part of the spell. If the target is 1 hp or more, the cure spell works instantly. But if the target is zero hp or below, it takes 1d3 minutes to heal instead. This can easily be fluffed as the dangerous wound requiring more time to fix, or just the way magic works, etc.
What you then get is a game where dropping to zero hp is highly undesirable and dangerous, but without the extra complexity of lingering injuries (albeit I personally like to use those as well ;) ) or 24 hr recovery breaks. PCs with cure spells suddenly have some hard decisions about when to heal, when to attack, and when to risk a drop to zero hp. If you want to make healing even more tactical/difficult, you might consider removing ranged and/or bonus action heals.
Similar delayed effects can be used for other kinds of traditionally instant cures - regenerating limbs might take 2d6 hours to grow back, or removing madness 1d6 days to subside, and so on. These injuries/conditions will then hang around for a fuller time, making them more dangerous/meaningful, but not so long that they bleed into the next adventure.
So there it is, Houserule #16: Tweak the Instant Cure spells. I hope it helps fix whack-a-mole in your game.
PS - Low Fantasy Gaming uses this approach (free PDF in the sidebar).
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