HE seems to be very intelligent. They had a lot of time to plot this chess/poker game and they seem to have had a counter for everything that has been tried.
Lots of psychopaths are intelligent. His facination with death and the dying process are big red flags here.
Hitler was amazingly brilliant, too. He heard voices. When the voices pleaded he not attack the USSR, for the first time, he ignored them. The voices ceased speaking to him. Up to that point, Hitler had it made. The rest is history.