When I'm deceased, by then the beast arise like yeast
To conquer peace leaving savages to roam in the streets

Meaning

When he dies, the apocalypse will descend on us. This has two possible meanings:

Right now Nas is the only thing keeping peace in the world.
The beasts are the grown from the seeds that he planted. By the time Nas dies, this force will come forth and successfully stampede the globe.

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