Dengar mini mine mayhem description says negative effects are applied to ALL enemies, however they only apply to 1 very frequently. Based on the description this shouldn't be an RNG based application but a crit based.
Hiya!
While Mini-Mine-Mayhem does inflict physical damage to all enemies,the negative status effects should only apply to those enemies that suffer a critical hit. So based on your description it appears only one of your enemies suffered a critical hit, which would inflict tenacity down for 3 turns.
So TLDR- If an enemy doesn't suffer a critical hit, the negative effects wont happen
Replies
While Mini-Mine-Mayhem does inflict physical damage to all enemies,the negative status effects should only apply to those enemies that suffer a critical hit. So based on your description it appears only one of your enemies suffered a critical hit, which would inflict tenacity down for 3 turns.
So TLDR- If an enemy doesn't suffer a critical hit, the negative effects wont happen