Is Shattered Strength bad?
Are you playing mesmer? If yes, take chrono.
Are you playing power shatter? If yes, take domination.
Are you playing a build that needs clone generation, excessive defense from stealth, or condition removal? If yes, take dueling/chaos/inspiration.
Illusions ranks as a poor 4th choice in the fight for the third specialization slot in a power shatter build. It’s only taken by a condition shatter build, which obviously requires MtD. It’s also taken in PvE builds…where shattered strength is obviously awful.