I particularly love the Dungeon Delver background since we have two commanders, so the chance of this staying active is better than normal
The Battle of the Pelennor Fields is made up of 18 individual cards that span all the way from Gondors capital of Minas Tirith to Saurons stronghold of Barad-dr in Mordor, with characters including Aragorn, Legolas, Gimli and Eowyn facing off against the Witch-king (on his Fell Beast), Gothmog and their armies of oliphants, orcs and more
I talked about what the party mechanic is and all the different cards that use the keyword
Its not a hard counter to Mewtwo, but if you get set up quickly you can win that matchup
Theater of Horrors is a lot like a Phyrexian Arena, except without the life loss, assuming youre aggressive enough