They're the Clam Creole Jazz Kings, apparently, and the effect is fun, where the player that summons Clam Session chooses a word, forcing everyone to sing a song with that word in it
Lightning Bolt was especially important at PT 1, as it was the best clean answer to Black Knight, Order of the Ebon Hand, White Knight, Order of Leitbur, and so on (since both Swords to Plowshares and Terror had giant weaknesses)
They elevated the game to new heights, attracting a diverse and passionate player base
In fact, one game I played in draft had two fliers grow to deal 15 points of damage with a couple of pump spells taking a game I thought I was winning the next turn with green dudes
Not the papal headgear, but rather the engineering term for a specific kind of joint between two objects coming together at a 90 angle, or the tool for making them