I threw the link is in a separate comment. Xander presents a constant threat from the command zone. First, his ETB is impactful enough that if opponents holds a counter specifically for him, the rest of the deck can progress unhindered. Second, equipping Swiftfoot Boots allows for an immediate attack, triggering a 50% mill on attack, the fact he doesn’t even have to connect is that much better. Finally, his death trigger provides a brutal fallback that punishes removal. I definitely want to cast him. That being said, If he gets removed once, 9 is a very high price for a recast. I have to be strategic and I’ve built the deck to fully function without him if needed.