Does the +1 bonus from the Improved Pact Weapon warlock invocation stack with the 2d6 extra damage from the Flame Tongue magic weapon?

Question

To build up from this similar question, does the warlock's +1 bonus from the Improved Pact Weapon eldritch invocation stack with optional bonuses, i.e. flame tongue when activated does 2d6 extra fire damage.

The relevant text for this:

Improved Pact Weapon:

In addition, the weapon gains a +1 bonus to its attack and damage rolls, unless it is a magic weapon that already has a bonus to those rolls.

Flame Tongue:

While the sword is ablaze, it deals an extra 2d6 fire damage to any target it hits.

There is no dispute between the +1 to hit, so I am confident in this bonus being applied. The issue is instead with the damage.

When the flame tongue is not ablaze, it would do x+1 (where x is the base damage). However, when ablaze, will it do x+2d6+1 damage? Or just x+2d6 damage?

Answer 1

Your Pact weapon will deal X+1(slashing/bludgeoning/piercing) +2d6(fire) damage.

You quoted all the relevant rules: the description of the Improved Pact Weapon says that you gain a +1 bonus to attack rolls and damage, unless it is a magic weapon that already has a bonus to those rolls.

A Flame Tongue has no such bonus, it "simply" adds 2d6 fire damage when it is ablaze: hence the requirements for Improved Pact Weapon are met and the weapon will deal X+1 + 2d6 total damage, being the first X+1 of the weapon damage type and the latter 2d6 of fire type.