Yes, COMBATIVE is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, M 3, B 3, A 1, T 1, I 1, V 4, E 1.

Is it a valid word?

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

inclined or showing an inclination to dispute or disagree, even to engage in law suits
striving to overcome in argument
having or showing a ready disposition to fight

Not playable in Scrabble US: DISPUTATIVE, AGONISTICAL, BATTLEFUL.