I doubt this is an original idea, but regardless:

Force of Disrupting Foil - X
Instant
You may pay X life and exile a blue card from your hand rather than pay CARDNAME's mana cost.
Counter target spell if its converted mana cost is X.
In keeping with "Force of Will is the carpet that we sweep all of Legacy's problem under", this is my attempt to chase after the "fixed" FoW in hopes of making legitimate Modern.
Here you keep the same color limitations, aspects of card disadvantage to punish the turn zero force, allow it to be as useful in stopping combo and other quick strategies (if they must maintain this arbitrary 4 turn limit), and have a natural curve of usefulness that declines once the game get mid to late so it's not game warping.

Thoughts?