"The Seven-fold Chant" isn't a real Magic: The Gathering keyword or ability—it doesn't exist in any official rules text, card, or mechanic. I can't explain how it works because there's nothing to explain.
It's possible you're thinking of a flavor name, a homebrew/custom card, or a mechanic from another game entirely. Magic does have real keywords that might sound similar in spirit—like Cascade, Storm, or Chapter abilities on Sagas (which trigger in sequence, sometimes evoking a "chant"-like progression).
If you can point me to the actual card or where you saw this term, I'll gladly break down what it really does, the rules nuance people trip over, and why it matters in Commander. I'd rather not invent rules and mislead you.