The fake Scott Ian head that gets hit with the sledge hammer is actually the silicon head created by Jerry Constantine in Scott Ian Gets His Face Cut in Half by Jerry Constantine (2012)
Scott Ian is usually the recipient of blood splatters on the series, but in an unaired test version of Blood and Guts with Scott Ian (2012) produced prior to Ian's involvement, director Jack Bennett and then production assistant Amanda Story were the ones deliberately drenched in fake blood. Bennett promised Story, who had volunteered to be doused in the test footage, that one day he'd get the chance to get her splattered on the show with Scott. He kept his promise and two years later she gets hit with the blood spurt in this episode.