In 22 BBY, several mastiff phalones ambushed several clone troopers under Jedi General Aayla Secura, Commander Ahsoka Tano, and Commander Bly, killing clone troopers Lucky, Flash, and Cameron. Another attacked Captain Rex as he protected a badly wounded General Skywalker at their ship's crash site. Rex shot one of its feet, frightening it off. A pair of mastiff phalones then went for Rex and Skywalker. Rex killed one, but the other charged at him and destroyed Skywalker's shelter. As it prepared to kill Skywalker, Wag Too, Tano, and Rex tied up the mastiff phalone's leg and left it alive.
At some point, Garnac and his hunting guild had one mounted in the bowels of their mobile base.
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