This has probably been discussed a long time ago, but I can´t seem to find an answer for it in rules or FAQ. And since I´ve recently included Frodo for the first time in a long while this question popped up.
When using Frodo´s ability to prevent damage, is the damage still considered to have taken place?
This is an important distinction when card effects play off wether a character has been damaged or not, such as with Hill Troll and Muck Adder.
The situation where it became relevant though was when we played Peril in Pelargir last night and we wanted to attach Alcaron´s Scroll to Frodo. The explicit intent was to have an enemy damage Frodo (making him unattach the scroll thus preventing the active location from sending too many enemies) and cancel it´s damage as per Frodo´s ability:
"Response: After Frodo Baggins is damaged, cancel the damage and instead raise your threat by the amount of damage he would have been dealt. (Limit once per phase.)"
The point is that as I´m reading Frodo he says " after Frodo Baggins is damaged", suggesting that the damage is considered to have taken place (and effects triggered by damage having met their requirement) even if later cancelled. I do seem to remember a ruling stating otherwise at some point though I can´t be sure.
Again, I think this was answered quite a long while ago but maybe I just need a memory jock.