I received a W2C adding box 12W to box 16 on the W2, as my employer had deducted it originally. I included the 12W in my taxes, and was wondering do I need to amend?

[DanielV01]

Yes.  You will need to report the HSA activity on Form 8889, which will generate once you enter the code W on the corrected W2.  This information must be provided to the IRS, although it is likely that you will not face additional taxes for the amended return.