Eldrazi runs Chalice of the Void on 0 or 1, which can lock out our one-mana spells entirely, so Force of Negation is crucial protection: it counters noncreature spells like Chalice of the Void itself and Kozilek's Command, and it can be cast for free on their turn by exiling a blue card. With mana value 3 it is unaffected by Chalice on 0 or 1 whether or not we pay its mana cost. It can't hit their creatures, though. Dauthi Voidwalker provides an evasive clock that pressures them while they're tapping out for Thought-Knot Seer and Reality Smasher. Daze is unreliable here since bouncing an Island to tempo them doesn't stop their colorless Eldrazi beaters, and Flow State is too slow against their fast clock.