Darkness Approaches [SRL-040] Common Insect or leaves the field because

or leaves the field because of an opponent's card effect while its owner controls it: You can inflict 500 damage to your opponent for each "Frightfur" monster in your Graveyard

then you can reveal 1 "Dark Magician" or 1 Spell/Trap Card that specifically lists the card "Dark Magician"

The first time this card would be destroyed by battle each turn

This card gains the appropriate effects if you Normal Summon it by Tributing these monsters

Darkness Approaches [SRL-040] Common Insect or leaves the field becauseSet: Spell Ruler Card type: Normal Spell Rarity: Common Discard 2 cards from your hand. Select 1 face up monster and flip it face down, but do not change its battle position.