Yes, HAMADRYADS is a Scrabble word!

Letter values in Scrabble US: H 4, A 1, M 3, A 1, D 2, R 1, Y 4, A 1, D 2, S 1.

Is it a valid word?

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

the nymph or spirit of a particular tree
large cobra of southeastern Asia and the East Indies; the largest venomous snake; sometimes placed in genus Naja

Also: king cobra, ophiophagus hannah, naja hannah.