It happened when I was at the site, 
Cavern Entrance, which says "Skirmish special abilities cannot be used".
I had in play the following cards:
Forearmed (Game Text: 
Skirmish: ...)
Elrond, Venerable Lord (Game Text: To play, spot an Elf. At the start of each skirmish involving Elrond, ...)
Vilya, Ring of Air (Game Text: Bearer must be Elrond or Gil-galad. 
Skirmish: ...)
Arwen, Daughter of Elrond (Game Text: Ranger. While skirmishing a Nazgul, ...)
Glorfindel, Revealed in Wrath (Game Text: When Glorfindel is in your starting fellowship, his twilight cost is -2. 
Skirmish:  ...)
Nenya, Ring of Adamant (Game Text: Bearer must be Galadriel. 
Maneuver:  ...)
Galadriel, Keeper of Nenya (Game Text: At the start of each turn, heal Galadriel. 
Skirmish: ...)
I was unsure which of these cards' effect texts I could still use.
I came to the conclusion that:
- I cannot use Galadriel or Glorfindel's special text because they are characters with 
skirmish- I can use Arwen and Elrond's special text because they are characters that don't say 
skirmish- I can use 
Nenya because it is 
Maneuver- I cannot use 
Vilya becuase it is a possession with 
skirmish- I cannot use 
Forearmed because it is an event with 
SkirmishWas I right?
Or could I have used 
Forearmed because it was played from hand, not already in play?