This is from the lyrics "The Edge of Dawn" from Fire Emblem Three Houses:
Yet still I hide
Behind this mask that I have become
My blackened heart
Scorched by flames of a force I can't run from
I am not sure if this 'complex' metaphor is something that's even allowed and if it's good style. There's three metaphor here, which means it's more than a metaphor within a metaphor.
The first metaphor is mask, which is inside of "I hide inside of the mask" and then it's followed up by "I have become the mask", the mask is the persona shown I guess, then there's the metaphor of hiding behind it, and followed up with the metaphor of having become the mask. It's all very convoluted and confusing. I've read a lot of poems from great authors, and I can't think of a similar pattern.
However, my question is whether this is also an oxymoron, because there is the contradiction, I am a mask and I also hide behind the mask as if I was wearing it.