Do bladesingers apply the song of victory Int modifier to the two-weapon fighting bonus attack, or do they still need the two-weapon fighting style?
I know that you don't add the ability modifier that you use for the attack to the damage, but what about ability modifier from other features? Is this a case RAI vs RAW?
Does song of victory need to say apply a bonus equal to the Int modifier for the bonus attack to benefit from it?
Sometimes I wish 5e has better wording on features.
Two Weapon Fighting
When you take the Attack action and attack with a light melee weapon
that you're holding in one hand, you can use a bonus action to attack
with a different light melee weapon that you're holding in the other
hand. You don't add your ability modifier to the damage of the bonus
attack, unless that modifier is negative.
Best Answer
This is a situation of "general vs. specific". The general rules for two weapon fighting are:
These are all specific rules that override the general rules about making a melee weapon attack based on a single extra condition: "when you put a weapon in your second hand".
There are even more specific rules, ones with multiple conditions - "when you put a weapon in your second hand and have ________". More qualifying conditions fits the definition of something being more specific.
"Song of Victory" is a specific rule that applies an additional bonus to all melee weapon attack damage rolls. It does not cite any restrictions about main hand vs. off hand, so no restrictions apply to it. The fact that value is equal to an attribute is irrelevant - it could be a static value, and it wouldn't change things.