Do I Add my Dex Modifier to my Slayer's Power Strike Damage?

Question

I have a Fighter (Slayer) from Heroes of the Fallen Lands. One of the class features is called Heroic Slayer, and it gives this benefit:

Benefit: You gain a bonus to the damage rolls of weapon attacks. The bonus equals your Dexterity modifier.

At level 1 you also get a power called Power Strike:

Power Strike; Fighter Attack
Encounter; Martial, Weapon
No Action; Special
Trigger: You hit an enemy with a melee basic attack using a weapon.
Effect: The enemy takes 1[W] extra damage from the triggering attack.

Do I add damage equal to my Dex modifier to both the melee basic and Power Strike, so that the total damage from a melee basic with a longsword to which Power Strike is applied is 2d8 + Str + Dex + Dex?

Answer 1

No.

Power attack is classified as extra damage and only adds to the damage roll, it does not add an additional damage roll.

Many powers and other effects grant the ability to deal extra damage. Extra damage is always in addition to other damage and is of the same type or types as that damage, unless otherwise noted. (RC 223)

Basically, you can't stack the same feature on the same damage roll twice. You already got it on the melee basic attack and extra damage modifies the original damage roll.

Answer 2

On the first reading it looks like you do.

The requirement for Heroic Slayer is that the damage be added to the "damage rolls of weapon attacks". The damage expression on Power Strike is 1[W], so that looks like a roll, and the power is listed as an attack and has the Weapon keyword.