Can a multiclass character use either of its spellcasting modifiers for spells?
When character multiclasses into multiple classes that can cast spells, which modifier do you use for casting the spell? Or do you use whichever you prefer?
Say, for an example, someone multiclasses Wizard into Warlock. Does the combination of classes even matter?
Is it the same for exclusive spells too? Like using Eldritch Blast, can you use your intelligence modifier instead of charisma?
Best Answer
Use the modifier of the class the spell comes from
Each spell you learn comes from its own class and is labelled as such (a spell learned from Pact Magic is a warlock spell). You must use the spellcasting modifier from that class's feature.
Even if a spell could have been learned from either class, what matters is how the individual learned it. If the character learned a spell from the wizard feature then it is a wizard spell and uses Intelligence even if it appears on other spell lists.
The Multiclassing rules detail that you treat your spells known or prepared separately for each class: