Played scenario 6-1 for the first time and was destroyed by one of the henchmen with what appears to be a bug. I have been playing through with Merisel solo. I was fighting the dwarven brother that required a Wisdom check before fighting and failed it. The card says he would then do 1d4+? damage to me but instead it dealt me damage equal to my wisdom roll. Afterwards, it did have him roll the d4 but since my hand was already empty I don't know if it would have dealt damage or not. This happened twice before I lost the scenario.
Playing on an iPad 4
Not a bug.
Silas is a "Monster", therefore he deals Combat damage to you equal to the difference between your roll and his check to defeat (at least, that's what I take you mean; if indeed he dealt damage equal to your ROLL - yeah, that's a bug). THEN, because *one character did not defeat Silas* (in your case - the only character), you're dealt *another* 1d4-1 Poison damagae, *in addition* to the Combat damage from the failed check.
Bottomlline: what might be tripping you up is, even though Silas' check to defeat is "Wisdom", not "Combat" - failing that check still deals Combat damage to your character, regardless of any other powers the monster has.