There are so many decks that want a Mirkwood Bats
As your foes search libraries, you'll gain a life (good for lifegain decks like Selesnya, Orzhov or Esper) and draw a card
If you have a way to loop it (like Crucible of Worlds plus Academy Ruins ), you can lock someone out of the game indefinitely
The ability reads: When this equipment enters the battlefield, create a 0/0 black Phyrexian Germ creature token, then attach this equipment to it. It was first introduced in Mirrodin Besieged back in 2011 as one of the mechanics designed to represent the invading Phyrexians
As such, Historic's banlist is fairly large since there's been plenty of powerful cards released in Magic Arena (largely thanks to bonus sheets)
I expect songs like A Pirate's Life to serve an important purpose in the Illumineer's Quest: Deep Trouble, Lorcana's new co-op game mode coming in Ursula's Return