Roxanne, starfell servant
Roxanne, Starfell servant has a bug where it will create multiple Meteorite’s in one turn. The card states that a meteorite is only created when Roxanne enters the battlefield or attacks. on occasion, a second instance of the meteorite will be created after the attack phase is over. I’m not sure of the trigger, but it happens sometimes. I’ve had this exploited where someone was able to destroy me with 8 meteorite’s in one turn in combination with a sorcery that copied creature abilities.
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DAC169#34537 commented
There's multiple cards that can duplicate abilities. For example, here's the enchantment Annie Joins Up adding an additional trigger of legendary creatures' triggered abilities, or that sorcery your opponent had used.