I guess things like Lure of Moria with "all" characters are interpreted as not being a single effect but rather a collection of effects and so follow the We Are Not Idle rule of "you can resolve the ones you can resolve and ignore the ones you can't". This is why I'd imagine that Elwing's Flight can be used on the same character several times.
Lure of Moria does still have an effect even if you have no Dwarf Characters. It resolves by readying 0 characters. It may seem odd, but they've ruled that "all" can be 0 before. But if the card said "Ready a Dwarf character" and you had no Dwarves, you couldn't play it, because "a" cannot be 0.
But if I have one dwarf character that is ready and one dwarf character that is exhausted, can I resolve the effect "ready all dwarf characters"? It is physically impossible for me to ready all dwarf characters.
I mean, I know I may resolve the effect. But it's a bit funny.
Edited by NathanH