Mustered Strength
The Fall of Nargothrond #333 (x3)
Treachery

When Revealed: Discard cards from the top of the encounter deck until an enemy is discarded. Put the discarded enemy into play engaged with the last player and attach Mustered Strength to it. Mustered Strength gains,"Forced: When a character is declared as an attacker against this enemy, deal 1 damage to that character."

Shadow: The attacking enemy makes an additional attack after this one.