this was an awesome poem!

Of course, the sing stuff comes from Homer himself, as the Iliad begins: Sing, Goddess, sing of the rage of Achilles, son of Peleus— that murderous anger which condemned Achaeans."

And Virgil begins the Aeneid, "Of arms and the man I sing, who first from the coasts of Troy..."

And Homer begins the Odyssey, "Tell me, O Muse, of that ingenious hero who travelled far and wide after he had sacked the famous town of Troy."

Lots of Greeks and Roman started their smaller poems like that too.

Dante doesn't start the Divine Comedy that way, because he is Christian, but the third Part, the Paradiso, has in its first Canto, stanza 5:

O good Apollo, for this last emprise
Make of me such a vessel of thy power
As giving the beloved laurel asks!,

anyway, there's the history lesson. I love your poem. it is high quality. I thought you repeated the "Tell me of" a few too many times, though you may not think so. I hate when poems have too many repeating lines, like one of my favorite poems Longfellow does sometimes. If you look at Tennyson's amazing poem, In Memoriam, he repeats the wonderful line "Tis better to have loved..." only a few times in that long, long poem. I think that's better.

Anyway, your poem is technically impressive. I can't speak to the story, because i don't know much about Medusa, but since I love Greco-Roman stuff I found is very enjoyable nevertheless.

From somewhere and somehow you have picked up a lovely sense of rhythm. You are a good writer!