Combining Game Effects and Combining Magical Effects – how does this relate to spells with multiple effects?
Here is the information from the Dungeon Master’s Guide and the Player’s Handbook that relates to my question.
Combining Game Effects:
Different game features can affect a target at the same time. But when two or more game features have the same name, only the effects of one of them —the most potent one— apply while the durations of the effects overlap. For example, if a target is ignited by a fire elemental’s Fire Form trait, the ongoing fire damage doesn’t increase if the burning target is subjected to that trait again. Game features include spells, class features, feats, racial traits, monster abilities, and magic items. (DMG p. 252)
Combining Magical Effects:
The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don’t combine, however. Instead, the most potent effect—such as the highest bonus—from those castings applies while their durations overlap. For example, if two clerics cast bless on the same target, that character gains the spell’s benefit only once; he or she doesn’t get to roll two bonus dice. (PHB p. 204)
How does the information above interact with spells that have multiple effects? I have used three spells as examples because each of them represents a nuance, but they could all combine to provide an answer: Blindness/Deafness (PHB p. 219), Bestow Curse (p. 218) and Contagion (p. 227).
For Blindness/Deafness (separate conditions): If this is cast twice, once to cause Blindness and once to cause Deafness, does this mean that the creature is both blind and deaf? Or, because it’s part of the same spell, only one of the effects is present – if so, which one?
For Bestow Curse (various curses): If two separate casters bestow separate curses on the same creature, do both curses remain in place? If so, how does we decide which one is active?
For Contagion (natural diseases): If you cast Contagion multiple times, to cause different natural diseases, would the creature have multiple diseases active, or only one of them?
I appreciate your thoughts on this.