"Last Turn" is a good Trap Card for turning a Duel you are about to lose into a surprise victory. All you need is your strongest monster on the field. The problem with "Last Turn" is that you cannot be sure if your opponent has a stronger monster in their Deck.
Instead of worrying about having the monster with the highest ATK, activate "Last Turn" when you have "Jowgen the Spiritualist" on the field. His effect prevents your opponent from performing a Special Summon. This means that they will not get the chance that "Last Turn" normally gives them to Special Summon their strongest monster. Your "Jowgen the Spiritualist" may be the only monster on the field and you will win the Duel!