Winter event quest

[Dimandokingo]

There's this one quest that I still can't complete. The quest asks me to defeat 3 syrillax guardian,pretty sure I defeated them already,or am I just doin it the wrong way?

http://uploads.tapatalk-cdn.com/20161223/d8f48ee4f2a2d2c089ce27edbc798945.jpg

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[Iuxor]

It's referring the higher Tiered set of bosses.... Not sure if it's even available in gold, but definitely plat. I only completed it when running with others in plat tier.