One of the Companions in the Fellowship is considered to be the Guide of the group during its quest.
At the beginning of each game of War of the Ring that Companion is Gandalf the Grey.
The Guide must always be the remaining Companion who has the highest Level. In case of a tie in Levels, the Free Peoples player can choose the Guide between the tying Companions.
Example: During the first turn of the game, the Fellowship player may replace Gandalf as guide with Strider, since both are Level 3 Companions.
The Free Peoples player may nominate a new Guide at the end of each Fellowship phase, or when, during the course of a turn, the composition of the Fellowship changes (due to a Character being separated or eliminated from the Fellowship).
Even when changing guides during the Fellowship phase, however, only a Character that has or shares the highest Level may be designated as the Guide.
The Character card of the Companion acting as the Guide is always kept as the topmost card of the Fellowship deck, so that his special abilities are readily accessible.
When a Companion is acting as the Guide, only his special ability that is marked “Guide:” (if present) can be employed. Any other special abilities listed on the card are not available, as they apply only after that Companion leaves the Fellowship.
If all Companions have left the Fellowship, the Ringbearers are alone and Gollum becomes the Guide of the Fellowship. When this happens, the Gollum Character card is placed in the Guide of the Fellowship Box.