Thundermare
{5}{R}
Creature — Elemental Horse
Oracle Text
Haste (This creature can attack and {T} as soon as it comes under your control.)
When this creature enters, tap all other creatures.
Watch Out
ETB trigger, not a cast triggerRules Note
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.