Yes, MERLIN is a Scrabble word!

Letter values in Scrabble US: M 3, E 1, R 1, L 1, I 1, N 1.

Is it a valid word?

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

(Arthurian legend) the magician who acted as King Arthur's advisor
small falcon of Europe and America having dark plumage with black-barred tail; used in falconry

Also: pigeon hawk, falco columbarius.