Traitor's Roar

Sorcery, 4{B/R} (5)
Tap target untapped creature. It deals damage equal to its power to its controller.

Conspire (As you cast this spell, you may tap two untapped creatures you control that share a color with it. When you do, copy it and you may choose a new target for the copy.)¹
Illus. Jim Pavelec

Gatherer Card Rulings [Nov 2009]

• 5/1/2008: If you use conspire to copy Traitor's Roar, but you don't change its target, the copy will resolve just fine but the original will be countered on resolution. That's because the copy will resolve first, and as part of its resolution, it will tap the targeted creature. Then, when the original Traitor's Roar tries to resolve, it will have an illegal target (since it must target an untapped creature).

Format Legality	Legal in Vintage, Legacy, Extended, MTGO Classic Banned in Standard
Printings (1/10)	Shadowmoor (Common)