The strangler fig grows long roots along the surface of a host tree, so it can kill the host by blocking its sunlight, and taking nutrients from the soil.
Base sentence: "The strangler fig grows long roots along the surface of a host tree so it can kill the host by blocking its sunlight and taking nutrients from the soil."
Fixed sentence: The strangler fig grows long roots along the surface of a host tree, so it can kill the host by blocking its sunlight and taking nutrients from the soil.
Explanation:
You just read it once so you know what you're working with, then you read it again and find what does and doesn't make sense with comma(s).