Omnicom's Calgary-based, interactive services firm Critical Mass hired David Armano as vice president, experience design. ... Directing duo David & Boris signed to Saville Productions for exclusive North American representation. ... Paul Renner, former creative director at Wieden + Kennedy, is returning to Arnold to join forces with Roger Baldacci, executive vice president, creative director. ... Post production shop Fluid added Ryan Lott as its newest composer. ... TM Advertising of Dallas hired Bob Brihn as creative director. ... Holmes Defender of the Faith, the production company founded by executive producers Jeff Armstrong (Satellite Films and A Band Apart) and Ben Dossett (Windmill Lane Productions and A Band Apart) signed multi-award winning director Bo Krabbe for North American representation.