2019-05-03 : A split card that’s both an instant and a sorcery is counted only once for Invade the City.

2019-05-03 : Army is a new creature type. It’s possible to control a nontoken Army (perhaps a creature with the changeling ability) and, through combinations of other cards, it’s possible to control multiple Army tokens. When instructed to amass, you may put +1/+1 counters on any of your Army creatures, and you may choose a different one each time.

2019-05-03 : If there are no instant or sorcery cards in your graveyard, you’ll amass 0. If you don’t control an Army, you’ll create a 0/0 black Zombie Army creature token that will die after Invade the City has finished resolving.

2019-05-03 : If you don’t control an Army, the Zombie Army token that you create enters the battlefield as a 0/0 creature. Any abilities that trigger when a creature with a certain power enters the battlefield, such as that of Mentor of the Meek, will see the token enter as a 0/0 creature before it gets +1/+1 counters.

2019-05-03 : Invade the City is still on the stack while you count your instant and sorcery cards in your graveyard. It doesn’t count itself.

2019-05-03 : The number of instant and sorcery cards in your graveyard is counted only as Invade the City resolves.