From the Comprehensive Rules 4.0:
Companion cards have resistance. This number represents a companion’s ability to withstand the lure of The One Ring. Some characters have a ring around their resistance icon, meaning they can be chosen begin the game as your Ring-bearer. (See building your deck.)
Companions preceding the Shadows expansion set (other than versions of Frodo or Sam) do not have their resistance printed on the card. These companions have a resistance of 6.
Allies have a resistance of zero.
. . .
Each burden on your Ring-bearer reduces the resistance of every companion in your fellowship by 1.
If your Ring-bearer’s resistance is reduced to zero, he is corrupted, and you lose the game. If the resistance of any of your other companions is reduced to zero, there is no immediate penalty, though your opponent may play Shadow cards to take advantage of this.
|Tokens||Twilight Tokens||Culture Tokens||Wounds||Burdens|
|Characters||Twilight Cost||Culture||Strength||Vitality||Resistance||Signet||Home Site||Site Number||Game Text||Lore||Collector's Info|
|Other (Modifier Layout)|
|Sites||Shadow Number||Site Arrow|