Peter F. answered 10/26/22
Published Author; Kinder-College English Tutor w/ 18 Years' Experience
Hi Ethan,
Your sentence is largely correct. Just replace 'in' with with to make it grammatically correct according to the given preposition.
His skin is pierced with thorns.
But yes, "pierced" is the right word/adjective for you to use in this context.

Peter F.
10/26/22
Ethan B.
So if i say, "im pierced with thorns"; That means i have thorns in me as i'm saying it?10/26/22