Spire Winder

Once you have the city's blessing, you have it for the rest of the game, even if you lose control of some or all of your permanents. The city's blessing isn't a permanent itself and can't be removed by any effect.

If your tenth permanent enters the battlefield and then a permanent leaves the battlefield immediately afterwards (most likely due to the "Legend Rule" or due to being a creature with 0 toughness), you get the city's blessing before it leaves the battlefield.

If you cast a spell with ascend, you don't get the city's blessing until it resolves. Players may respond to that spell by trying to change whether you get the city's blessing.