Question: [Our Mishnah exempts Shogeg] when he thought that it is Chulin (and there is no loss if he is Metamei it). If he knew that it is Terumah, but thought that it is permitted to be Metamei it [what is the law]?

Answer: We learn from [the Seifa of our Mishnah]. Kohanim who were Mefagel in the Mikdash b'Mezid, they are liable;

Question: What is the case?

If he thought that it is Chulin, does Pigul apply to Chulin?! (We must say that the Pesul of Mis'asek applies only to Shechitah, and here we discuss other Avodos (ACHIEZER YD 4). Alternatively, also the Pesul of Mis'asek is included in 'Pigul', for it is due to intent. (PF) One could say that he happened to say 'I will eat this animal tomorrow', but (even if he thinks that it is his) this is unlikely, especially if we discuss Avodos after Shechitah, and he engages with the blood.

Answer: Rather, the case is, he knows that they are Kodesh, and he thinks that it is permitted to be Mefagel with Kodesh.

And here, he knows that it is Terumah, and he thinks that it is permitted to be Metamei it.

(Rav Huna citing Rav): [The Chiyuv for Menasech in our Mishnah] is for mixing (Yayin Nesech with permitted wine. It cannot be pouring libations to idolatry. Since he is Chayav Misah, he is exempt from payment!)

Question: If he poured [to idolatry] and [afterwards] mixed, [what is the law]?

Answer: Initially he is Chayav Misah [for pouring], and afterwards [he is obligated] payment for mixing].

Rebuttal #1 (R. Aba): Exert yourself [and you will find the answer]! If one murdered and broke a flask (i.e. he killed through breaking it, do we say that) initially he is Chayav Misah, and afterwards payment?! (We hold that he does not pay!)

Rebuttal #2 (R. Yosi): Exert yourself [and you will find the answer]! If one burned another's stack on Shabbos, [do we say that] initially he is Chayav Misah, and afterwards payment?!

Support (for Rebuttals): If one was Metamei, Medame'a, or Menasech b'Shogeg, he is exempt. If he was Mezid, he must pay, and R. Yochanan said that it is a fine. (This connotes that all of them are the same, i.e. there is no Chiyuv Misah. Menasech is only mixing. We explained this like PNEI MOSHE.)