An apparatus for electroplating a layer of metal onto the surface of a wafer includes an auxiliary electrode that is configured to function both as an auxiliary cathode and an auxiliary anode during the course of electroplating. The apparatus further includes an ionic current collimator (e.g., a focus ring) configured to direct ionic current from the main anode to central portions of the wafer. The provided configuration effectively redistributes ionic current in the plating system allowing plating of uniform metal layers and mitigating the terminal effect. In one example, the auxiliary electrode functions as an auxiliary cathode in the beginning of electroplating when the terminal effect is pronounced, and subsequently is anodically biased.