I really like how Alexander became a scion to Clark. Enjoyed watching him learn about his powers. The heat vision was funny.
Great to see Luthor Mansion again -- or whats left of it.
Faceless double for Lex. Check.
Obligatory Oliver/Chloe mention. Check.
DARKSEID!! Did they know Rosenbaum would be returning when this was filmed? I'd imagine so. My guess is that yeah, Lex is revived at the cost of Lionel's life (depending on whether he shows up again). And nice to actually see Lex's headstone after all this time.
The episode was well played out. Good one to start a break on. Now alt-Jonathan is coming? Also, nice that they'll be showing the pilot, but a 10 year special would be better.