Yes, REVERSION is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, V 4, E 1, R 1, S 1, I 1, O 1, N 1.

Is it a valid word?

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

(law) an interest in an estate that reverts to the grantor (or his heirs) at the end of some period (e.g., the death of the grantee)
(genetics) a return to a normal phenotype (usually resulting from a second mutation)
a reappearance of an earlier characteristic
turning in the opposite direction
returning to a former state
a failure to maintain a higher state