Radiant Destiny

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
As this enchantment enters, choose a creature type.
Creatures you control of the chosen type get +1/+1. As long as you have the city's blessing, they also have vigilance.

The Lost Caverns of Ixalan Commander

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
As Radiant Destiny enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +1/+1. As long as you have the city's blessing, they also have vigilance.

Rivals of Ixalan Promos

Rivals of Ixalan

A permanent is any object on the battlefield, including tokens and lands. Spells and emblems aren't permanents.

Ascend on a permanent isn't a triggered ability and doesn't use the stack. Players can respond to a spell that will give you your tenth permanent, but they can't respond to getting the city's blessing once you control that tenth permanent. This means that if your tenth permanent is a land you play, players can't respond before you get the city's blessing.

Gaining vigilance any time after the moment you choose to attack with a creature won't cause that creature to become untapped, and losing vigilance after that time won't cause it to become tapped.

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.

If you control ten permanents but don't control a permanent or resolving spell with ascend, you don't get the city's blessing. For example, if you control ten permanents, lose control of one, then cast Golden Demise, you won't have the city's blessing and the spell will affect creatures you control.

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.

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.

Some cards get power, toughness, and/or abilities once you have the city's blessing. If another card has an ability that triggers when creatures with certain characteristics enter the battlefield (such as Mentor of the Meek or Elemental Bond do), use the entering permanent's characteristics after you have the city's blessing to determine whether those abilities trigger. This is true even if the entering permanent is your tenth permanent.

To choose a creature type, you must choose an existing creature type, such as Vampire or Knight. You can't choose multiple creature types, such as "Vampire Knight." Card types such as artifact can't be chosen, nor can subtypes that aren't creature types, such as Jace, Vehicle, or Treasure.