Artifact // Creature — Dinosaur Skeleton Horror
Artifact
When this artifact enters, target opponent reveals their hand. You choose an artifact or creature card from it. That player discards that card.
Craft with two creatures {5}{B} ({5}{B}, Exile this artifact, Exile the two from among creatures you control and/or creature cards in your graveyard: Return this card transformed under its owner's control. Craft only as a sorcery.)
Creature — Dinosaur Skeleton Horror
Menace
Whenever this creature enters or attacks, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
This card's ability triggers when it enters the battlefield, not when it's cast. Effects that double ETB triggers (like Panharmonicon) work here. Countering the spell prevents the creature from entering, so the ETB won't fire.