Attack!" When Alister activates the first effect of that monster, he announces, "Machina Unclaspare activates when its added to the hand!" When Alister activates the second effect of that monster, he announces, "Machina Unclaspares effect activates when its Summoned!" When Alister Summons "Overdrive", he announces, "Overdrive!" Most of the time when Alister declares an attack with that monster, he announces, "Overdrive
My best guess was Brian was making a top-down bard
Perhaps Theros Beyond Death provided some new additions to your Hydra deck
This card is incapable of creating any value on its own, which makes it difficult for the card to see play past Commander a format where players have lots of time to set up their board states
9 - Rocket's Mewtwo ex (Ruby/Sapphire: Team Rocket Returns - Foil Card - 99/109) This base Ruby & Sapphire set paid homage to the classic Team Rocket set from the Wizards of the Coast era, but also introduced a few new mechanics: Pokmon with two types, namely their original type and Dark, and Pokmon that lost their main type and became exclusively Dark Pokmon
