The return of the Phoenix.
In what may be an act of divine retribution, Stavros Cassadine, Luke's number one nemesis, returned to Luke and Laura's life again. With the exception of not finding Lulu, Luke probably thought things were going to go his way when he shot and killed Helena. Imagine his surprise when another face he saw in its final throes of death twice in the past resurfaced on Cassadine Island. As many times as Luke had been cursed by a Cassadine, he was the one cursing them now. Helena was responsible for freezing and bringing Stavros Cassadine back to life once before, what brought him back to life this time? Perhaps he never died as Luke and Laura thought.
In 2001 Stavros resurfaced in Port Charles after Helena revived him from his cryonic suspension from below General Hospital. He creepily stalked Laura in a sense; leaving behind mementoes for her to find. Before Luke could have a go at Stavros, Stefan broke free from jail and found Stavros alive on Wyndemere Island. His remedy was to tie Stavros up in a coffin. He was freed by the PCPD at which point he took an opportunity to wreak more havoc with Helena. While she was doing her thing and being captured by the PCPD, Stavros was fighting Luke Spencer. Luke again had the upper hand and Stavros seemed to voluntarily meet his demise falling down a shaft of some sort.
Tell us if you remember how Luke got the upper hand with Stavros in both instances before Stavros died.