In 5e, if a spell is only learned as a part of having a weapon with the ability to cast it, because it is technically an attack with the weapon and not me directly casting the spell, would I add the damage bonus to the damage roll?
I have a great axe that allows me to cast call lightning 3 times per long rest. It's a homebrew version of Stormbreaker from The Avengers. My DM and I just aren't sure if we should add the bonus to the damage for the spell being cast from the weapon itself. We are just wondering if there are any official items with similar abilities, and how they would work.
By damage bonus, I mean the relevant modifier you add to damage rolls for attacks with the weapon.
You don't add your weapon damage bonus to spells it grants you.
Since it's a homebrew item, its function is up to your DM.
However, the only relevant damage bonus to either greataxes or call lightning are the Strength modifier to damage, and any magic weapon bonus.
If the weapon instead dealt additional lightning damage on a successful melee hit, then you would still add your Strength modifier as normal.