I know that the effects of a spell don’t combine if it is cast multiple times. Only the most potent effect would be applied. In our last game, this topic came up in regards to the Harm spell. Harm was cast on an opponent. He failed the save, took a lot of damage and his hit point maximum was reduced drastically. A turn later, he got slammed again with Harm. This time, he succeeded on the save and very little necrotic damage was dealt. Then, the discussion started whether his hit point maximum would now be further reduced or if the “more potent” Harm spell takes precedence.
Naturally, I argued that his hit point maximum would not be reduced further, because effects of the same spell cast multiple times don’t stack. The counterargument was, that the necrotic damage dealt by the Harm spell is clearly an effect of the spell. And no one would argue, that the damage dealt by two consecutive Harm spells would only be applied once. So now I ask you:
Can the hit point maximum be reduced repeatedly with multiple Harm spells?