The word assaulters is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 12
Highest Scoring Words With Friends™ Plays In The Letters assaulters
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Seven Letter Word Alert: (24 words)
artless, assarts, assault, asserts, assures, atlases, aurates, austral, estrual, lusters, results, russets, rustles, saluter, salutes, searats, seastar, slaters, sutlers, taluses, tarsals, tassels, trusses, tussles