Yes, HALCYONS is a Scrabble word!

Letter values in Scrabble US: H 4, A 1, L 1, C 3, Y 4, O 1, N 1, S 1.

Is it a valid word?

HALCYONS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(Greek mythology) a woman who was turned into a kingfisher
a large kingfisher widely distributed in warmer parts of the Old World
a mythical bird said to breed at the time of the winter solstice in a nest floating on the sea and to have the power of calming the winds and waves

Also: genus halcyon.

Not playable in Scrabble US: ALCYONE.