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, or the most recent effect applies if the castings are equally potent and their durations overlap.

For example, if two clerics cast bless on the same target, that character gains the spell’s benefit only once; they do not get to roll two bonus dice.

However, when two spellcasters act together they can cast spells in unison for increased potency. In order to do this, the two spellcasters must be adjacent to one another, or otherwise coordinate their positioning appropriately, and act simultaneously via readied actions or other, similar, means. For example, two spell casters might perform a spell combo from opposite sides of the target.

In order to successfully combine their spells, each spellcaster must succeed on a proficient spellcasting attribute check of DC 10 plus the level of the spell they are casting (cantrips are level 0 spells). If either of these skill checks fail, the spells function normally.

If these skill checks succeed, both spell attack rolls have advantage.

Spell Interaction

Some elements or damage types cannot be effectively combined, while others make for especially potent combinations. If one spell is boosted by another, then its damage roll has advantage.

Boosted Elements

• Air boosts Fire
• Fire boosts Earth
• Earth boosts Water
• Water boosts Air

Opposing Elements

• Air and Earth
• Fire and Water

Boosted Damage Types

• Bludgeoning boosts Bludgeoning
• Cold boosts Bludgeoning and Necrotic
• Lightning boosts Thunder
• Necrotic boosts Acid
• Poison boosts Necrotic
• Piercing boosts Poison
• Radiant boosts Fire
• Slashing boosts Poison
• Thunder boosts Bludgeoning

Opposing Damage Types

• Cold and Fire
• Necrotic and Radiant