Impilturan Demonslayer Attack 20Demonbane Flurry

Your weapons work in deadly concert to unravel the very essence of your foe and singe its nearby allies.

Daily        Arcane, Weapon
Standard Action      Melee weapon

Target: One creature

Attack: Strength vs. AC (main weapon and off-hand weapon), two attacks

Hit: 3[W] + Strength modifier damage per attack, and the first attack that hits also deals ongoing 10 damage (save ends).
    If the target is a demon, in addition this damage ignores all resistances, and until the end of this encounter, when the demon takes ongoing damage, its allies within 2 squares take the same amount of damage.

Published in Forgotten Realms Player's Guide, page(s) 58.