One use only. Right before the battle (during step 7 of the Deployment Phase Sequence), the bearer must place a single Forest Terrain Feature that must be no larger than 10" in length and 6" in width on the Battlefield, not in contact with any other Terrain Feature except Open Terrain, more than 1" away from all enemy units, and with its centre within 12" of the bearer. While inside this Forest Terrain Feature, friendly models gain a +1 Casting Modifier for Augment, Hex, and Universal spells, and add (+1/+1) to the Power Level of Totem Bound Spells they cast.
The effects last until the end of the game, even if the bearer is removed as a casualty.