User blog comment:Linathan/Unit Spotlight: Crescendo Megurine Luka/@comment-26040524-20150228220134

Nice analysis. Other analyses I've read portray Luka's LS very positively in that she can save one or even two slots on your team (healer, status immunity, she can even do some passive BC generation). Any extra damage that she does is a bonus. I can see both the positive and negative arguments over her LS.

Another aspect that could be emphasized more is that Luka is the only dark element dedicated healer available, as far as I know. That is significant in that only a light element enemy will put her in any danger. For players who are concerned about elemental weakness as they build their teams, having different elemental options for healer/pseudohealer can be important.