There's several of them now, and definitely worth glomming together to make spell-spammy attack decks
This definition can also be expanded to include other permanent card types, such as artifacts, enchantments, planeswalkers, and lands
Im using Breya, Etherium Shaper here, but cards like Grave Titan and Wurmcoil Engine work too: Ashnod's Altar and Nim Deathmantle need to be in play
This means that Xancha will be causing problems for other players at the commander table regardless of whose she's attacking
Im no expert on the subject, but my understanding is that boxers are paired up against each other based on weight class
Like other trading card games like Pokmon and Magic: The Gathering, there are different mechanics and powers involved with game play