As noted in the main mechanics article, older cards will receive an update to now say "amass Zombies N," and if the Army creature you put +1/+1 counters on isn't already a Zombie, it becomes a Zombie in addition to its other types
When you do, gain control of target creature that player controls with power less than or equal to the tapped creatures power for as long as you control Nihiloor
In that situation, try to look for other strategies, often similar, that you could effectively superimpose on top of your existing list, preferably with many shared cards
For Diabolic Convergence, each legendary permanent you control will reduce the cost of the spell
But when you get into the game, it may seem a bit overwhelming
And you can see why, given the clip is so infuriatingly uninformative, and especially the choice to show the classic cards in very many different languages, and then finishing on the news that it will release simultaneously worldwide