you dont even need to touch her field spell. if you're using vassal, just summon her before you last turn. she will return in the same spot ready for the last turn.
If you use RE Slash deck, you can summon Vassal on the last turn, and when the field spell tries to banish Vassal, respond with RE Slash's effect to protect Vassal.
Regardless, Red Eyes Slash's effect still nulls and destroys Future Visions, as I just did it to protect my Vassal. Otherwise I would've lost by deck-out on the next turn.