וַאֲנִי אַקְשֶׁה, אֶת-לֵב פַּרְעֹה; וְהִרְבֵּיתִי אֶת-אֹתֹתַי וְאֶת-מוֹפְתַי, בְּאֶרֶץ מִצְרָיִם
And I will harden Pharaoh's heart, and multiply My signs and My wonders in the land of Egypt ... Shemot 7:3
There is a long standing ambiguity in Judaic tradition as to why the Lord found it necessary to interfere with Pharaoh's free will by "hardening" Pharaoh's heart. I'll tell you why the Lord played mind games with Pharaoh - because the Lord needed to do it to magnify His signs and wonders. You see, without Pharaoh's participation in this manner, the Lord's signs and wonders were impotent. The Divine Magician's magic fell flat without Pharaoh. Pharaoh Herself powered the Lord's magic.
Let's play. My way.