Mirror-Style Master
Creature — Human Warrior
Oracle Text
Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Whenever this creature attacks, for each attacking modified creature you control, create a tapped and attacking token that's a copy of that creature. Exile those tokens at end of combat. (Equipment, Auras you control, and counters are modifications.)
Watch Out
Copies don't copy counters, equipment, auras, or other external modifications. A copy of a transformed card copies only the front face. If the copy enters the battlefield, it triggers its own ETB abilities.
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.