From the Comprehensive Rules 4.0:
When the assignment phase is complete, each defending character will fight in a separate skirmish phase. In an order decided by the Free Peoples player, skirmishes are resolved one at a time by conducting a skirmish phase for each.
Once a skirmish phase has finished, the Free Peoples player must select another defending companion (one who is still assigned to a minion), and perform another skirmish phase.
Perform skirmish actions
During each skirmish phase, players may perform skirmish actions (special abilities on cards in play with “Skirmish:” and events with that keyword) using the action procedure. Each skirmish action lasts only for a single skirmish. When all players consecutively pass, proceed to resolve that skirmish.
Resolve that skirmish
If the total strength of one side is more than the strength of the other side (but less than double), the side with the most strength wins that skirmish. (If there is a tie, the Shadow side wins.) Place one wound on each character on the losing side.
When the winning side has one or more characters with the keyword damage +1, then each losing character takes one additional wound for each damage +1. (Damage +2 adds two wounds, and so on.) This is called a damage bonus, which may be added to or removed by various effects.
If the total strength of one side is at least double the total strength of the other side, all the characters on the losing side are overwhelmed and killed (regardless of how many wounds or how much vitality each has). When a character is overwhelmed, that character does not take any more wounds — he simply dies.
A skirmish phase ends after all actions triggered by winning or losing that skirmish have resolved. A surviving minion or companion may skirmish again this turn if the fellowship makes another move (or if the minion has the keyword fierce).
Skirmish Phase Summary
- Free Peoples player chooses a skirmish.
- Players perform skirmish actions.
- Resolve that skirmish and assign wounds.
- If any skirmishes are unresolved, repeat this procedure.
After all normal skirmishes are resolved, surviving minions with the keyword fierce must be defended against a second time.
Players perform another assignment phase and then complete a separate skirmish phase for each fierce skirmish.
Assignment Phase (Fierce)=
Players may again perform assignment actions (special abilities on cards in play with “Assignment:” and events with that keyword) using the action procedure.
The Free Peoples player then assigns defenders just as during the regular assignment phase, and then Shadow players assign any fierce minions that remain unassigned.
Skirmish Phase(s) (Fierce)=
Then each defending companion fights in a separate skirmish phase, just as during the regular skirmish phases, in an order decided by the Free Peoples player.
When all skirmishes (both normal and fierce) have been resolved, proceed to the regroup phase.