A fairly small, long-tailed bird of lowland and foothill forest on Mindanao and Basilan. Overall dull blue in color with a paler belly. Often pumps tail up and down. Forages in the understory for insects and often joins mixed-species flocks. Similar in size and shape to Celestial, Short-crested, and Black-naped Monarchs, but Mindanao Blue-Fantail is darker blue with a contrasting pale blue brow, tail, and wing patch. Song consists of a slightly ascending series of medium-pitched, upslurred whistled notes, increasing in volume. Also gives a sharp “wik!”