Using the Eldar's most advanced warp technology, a phase field allows the wearer to shift between realspace and the webway, 'phasing' in and out of reality. This means the wearer can make short teleportations across the battlefield. The phase field is used instead of moving normally. Nominate a direction for the model to move in. The model moves 3D6" in that direction, ignoring any intervening terrain or models. A model using a phase field may not use fleet of foot on the same turn, but may shoot and assault as normal.
Phase Field
Source: Codex: Harlequins, p. 12