1)
To which great judgments is Hashem referring?
1.
Seforno: To Makas Bechoros and the drowning of the army in the Yam-Suf, which came as a punishment Midah Keneged Midah for their cruel treatment of Yisrael. 1
1
Seforno: The purpose of the other plagues were to bring Pharaoh to do Teshuvah (even after the drowning of the army - See Beshalach, Shemos 14:18 [Seforno]) and to demonstrate Hashem's Omnipotence to Yisrael (See Shemos 7:17, Shemos 8:18, Shemos 9:29 and Shemos 10:1 & 2).
