User blog comment:JmLyan/Pixia, the Faerie Queen/@comment-25235491-20140811195350/@comment-7481207-20140811205723

Her spells are sort of double-casts yes, but you can single-cast them as well.

Her base armor is very low though, so she is very squishy when she doesn't have the defensive buff, and not way too strong when she does have it.

Joy Tripwire is for when you need healing rather than damage and the CC, depending on the situation, it might save your ADC where ordinary Tripwire would not. It is also much better when there are no enemies around and you want to make your ally healthier.

And Baron Nashor's damage reduction only applies to damage dealt to him (since a patch a long while back). Joy's damage reduction is equal to that of exhaust at rank 3 while lasting half a second longer, but without the slow, attack speed reduction and armor/mr reduction. And while Joy can hit several targets, it being one of the curved parts of the ultimate makes it harder to aim. The potential effect from hitting all 3 on a single target is great, but also even harder and hitting more than one enemy with all 3 doubtlessly requires skill.