I personally think you did one big mistake about it.
You should have released 3 zombie skins on harrowing and then next patch 3 zombie slayer skins.
This would have been way better because for harrowing "slayer" theme make no sense (at least for me) and at the same time it would make sense as story.
Day 1. zombies come out from nowhere and the rift is filled with zombies.
Day 11. 3 champions come out to clear the rift from zombies.
Something like this.
I think that if you proceeded this way much more people would have like this harrowing skins.
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