Part of the reason that this can be off, is perhaps that Selene is a Titan from Ancient Greek myth, and has nothing to do with vampires except in modern movies taking her name in vain. Selene - Wikipedia … and then, the working is a bit random with “dark ones”. There’s no mention f you actual personal goals or what you are trying to achieve.
As Humans are creator beings though, and can get a lot to work under their own ability, you can make something out of anything, all you needed was the inspiration
So if you take the poem and it’s translation with what you said:
English translation:
Oh goddess of the darkness, mother to the immortal, let me be reborn as your child. Let your light absorb my own. Allow me passage to the darkness as from your immortal womb into the arms of your children to whom I will call brother. Oh moonlight, let me be reborn as your child. Guide the dark ones to me so I shall be born again.
I read this as asking moon energy and beings associated with that to help you learn and guide you for your highest good.
It reminds me of the Gateway Experience tapes that include an affirmation that calls out to beings of a level of ability that is as good as or higher than yourself to help you along the way. - this part is missing from the ode, and opens the door to freeloaders, parasites and other time wasting beings.
I think it would help to affirm why you want to blend with the moon goddess. Is it health and longevity? Then include that in your affirmations and see yourself living long with full health and wellness.