I'm making a Feral Tiefling with the Devil's Tongue set of traits, and as written the spells gained from being a Tiefling use Charisma for spellcasting and a DC. Later, I'm going to be making him an Eldritch Knight
My question is: Will I then have two different spellcasting attributes (Charisma for Tiefling spellcasting and Intelligence for Eldritch Knight spellcasting)? Or will everything then be governed by Intelligence?
You would have two spellcasting attributes. Charisma governing your Tiefling spells and Intelligence governing your Eldritch Knight spells. The reason for this comes down to how you obtained the ability to use each spell. Spells that come to you innately such as, racial and Sorcerer spells are based off of Charisma, while spells that are learned through study, such as Wizard and Eldritch Knight spells are based off Intelligence. Therefore, when you become an Eldritch Knight it would make since that the spells given by your heritage would still be cast using your Charisma. I've run into this myself playing a Tiefling Wizard. I've found that if it gets too confusing switching between the two modifiers, most DMs will let the technicality slide and allow you to use your dominant ability. If this is not allowed by your DM, you could take the time and gold in game to study and relearn the spells as wizard spells.
