The final season of Rowena MacLeod began as a somewhat villainous entity on Supernatural, her allegiance soon softened from evil to mischievous and, finally, to trustworthy. Rowena became particularly attached to the younger of the Winchester brothers, Sam, and he aided her spell casting on several occasions throughout Supernatural's later seasons. Always the more studious of the brothers, Sam had previously dabbled in basic spells by himself, but nothing close to Rowena's level.
Rowena and Sam's friendship was hindered by the tragic prophecy that the hunter had been fated to kill the witch and, fulfilling that destiny, Rowena was one of the first major casualties of Supernatural's final season. Rowena gave her life in order to help defeat the souls God had released from hell in the previous season's finale episode, and Sam had to be the one to deal the final blow. Sam has carried the weight of Rowena's death ever since, and that grief was pulled into full focus for Supernatural's latest episode, "Golden Time."
This magic-themed adventure centers around a family of opportunistic witches who attempt to ransack Rowena's abandoned home for rare spells and coveted ingredients, while Sam Winchester also pays the lair a visit in an attempt to help deceased fellow hunter, Eileen. Upon arrival, Sam discovers that Rowena had actually bequeathed her collection of arcane treasures to him, effectively naming the Winchester brother as her magician's apprentice. Sam went on to prove that he wasn't entirely unworthy of Rowena's trust, revealing that he had learned enough from the witch to complete her unfinished resurrection spell.
For the remainder of "Golden Time," Sam acts more like a witch than a hunter, putting together a hex bag to take down his opponent, while brother Dean sticks to the tried-and-trusted brawn and bullets method. Back at the bunker, Sam's magical prowess even allows him to conjure a naked woman out of thin air. This growth in casting spells doesn't go unnoticed by Sam's brother, with Dean questioning the sudden change in approach, and while Sam attempts to play down his new skill as a lucky break, it's clear that he has actually evolved into quite the adept sorcerer under Rowena's guidance.
With Supernatural in its final season, it's obviously a little late in the day for Sam's character to change dramatically and for him to start routinely slinging spells in battle. However, there are two potential ways in which the lessons taught by Rowena could feature in Supernatural's finale. Viewers have already seen God amassing his forces by bringing Lilith back to life; it makes sense that the Winchesters would also need a boost ahead of Supernatural's final battle, and having one of the brothers inherit Rowena's catalog of spells is a neat way of achieving this, while also giving the popular witch some sort of presence in the show's climax.
On a more sinister note, Supernatural has already teased Sam becoming a villain by the final episode, and has shown a vision where he possesses powerful psychic abilities. Although this was blamed on demon blood in the illusion itself, could Sam's renewed affinity for magic help push him down a dark path and bring God's dream Winchester vs. Winchester battle ever closer.
Supernatural continues with "Last Call" December 5th on The CW.