Patch 24.2.2.149417 (2022-09-09):
Now reads: Whenever damage is dealt to a Frozen enemy, deal 1 more. (previously: Whenever damage is dealt to a Frozen enemy, double it.).
Patch 21.6.0.124497 (2021-11-02):
Now reads: Whenever damage is dealt to a Frozen character, double it. (previously: Whenever damage is dealt to a Frozen enemy minion, destroy it.)