Are you predicting that a big portion of the mentor players move to outcome?
If so, null rod seems like a very strong call.
If they move to something like gifts than it's less clear to me. Gifts does run more artifact mana than mentor, but it also runs drain and some higher cost spells where you might be better served by more low to the ground threats.
To me, I suspect that the primary blue kill now will be tinker BSC, which makes me what to have more metamorphs. They also double as extra thorns / spheres once the first one is resolved and can usually at least keep you on par with opposing creatures.
Not really sure how things shake up though.