5e Harm

In 5e, Harm reads:

You unleash a virulent disease on a creature that you can see within range.

The target must make a Constitution saving throw.

On a failed save, it takes 14d6 necrotic damage, or half as much damage on a successful save.

The damage can’t reduce the target’s hit points below 1.

If the target fails the saving throw, its hit point maximum is reduced for 1 hour by an amount equal to the necrotic damage it took.

Any effect that removes a disease allows a creature’s hit point maximum to return to normal before that time passes.

In Baldur's Gate 3 however, on failed save, the target has its max hp reduced by 14d6, but there is no damage.

This means the spell almost has the intended effect on a target with all its hit points, but not on targets missing some.

Also, it doesn't trigger effects that work with damage.

Essentially, BG3's version is not as good, and is flawed.

This mod fixes this, by making Harm actually deal the 14d6 damage (they still won't kill the target) and then reduce the target's maximum hit points for the amount dealt.

This means damage riders will also be taken into account.

So to illustrate, say you cast Harm on a target with 68/108 HP while having 4 Lightning Charges, and they fail the save.

Say you roll 14d6 = 34.

Target loses 34 max HP.

Outcome: 68/74 HP

Total damage is 34 necrotic + 4 lightning.

Target loses 38 current and max HP now.

Outcome: 30/70 HP

Vanilla version is not as good by a long shot, and is dowright useless when the target isn't at or near full HP, unless it has massive healing capabilites or something, which is very rare to non-existent in the game.

There is a point where you have better results when target resists the save than when it fails with BG3's version, which is a design flaw, probably left by devs because reducing the HP for the same amount as the damage dealt is a bit tricky due to engine limitations.

Now there is a fix, enjoy!

While I was at it, I also made the duration actually be 1 hour (600 turns) so it's really accurate to 5e, even if that has barely any effect on anything.

Trivia: I discovered this while working on Umbral Archer and its Arrow of Harm. It bothered me so I fixed it. Naturally, Umbral Archer will work with this fix, but will also work without it, in the vanilla way.