Its really good at generating card advantage and messing with your opponents plans, so you get to stay in control while setting up your big moves
If you put it on top of your library, you cant cast it using madness
The people expecting Xenagos to stay at $40 were betting on a two-color planeswalker being so good that it would see play as a four-of in multiple tier 1 decks, which never seemed likely to me
if heads,prevent all effects of an attack, including damage done to hoop unbound during this turn
However, Commander games can be pretty long and require a lot of planning to arrange and then a lot of effort to play, so cards destroy all lands in play like Armageddon, Devastation, and Ravages of War can be extremely frustrating to play against if no one can counter them
That's not great, but if you have anything more than two creatures in play, this can end the game -- often literally, not just effectively