Spirits of the Fay are not deployed with the rest of the army, but follow the entry rules for Ambushers instead.
When they appear, they must be placed in either a forest or a water feature anywhere on the table, but otherwise follows the rules for Ambushers as normal. If no forest of water feature is present, they may enter from any table edge using the normal rules.
As long Spirits of the Fay remain partially within one of these terrain features, they may replace up to D3 Wounds lost earlier in to game at the end of each Close Combat phase.