Unexpected result from Skorn, BMP and H. Burster



I had a full field of wraithlings, a Bloodmoon Priestess and a Horror Burster.
My opponent played Skorn.
My Bloodmoon Priestess became the Horror and generated 8 wraithlings around itself.

I would have expected the Horror not to generate Wraithlings as if it still was the Bloodmoon Priestess.

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