The best way to beat a dangerous asteroid might be another asteroid.
Not by using it to collide with the dangerous asteroid, but to wobble it.
Possible by setting out a net to “catch” the dangerous asteroid, with the net being cabled to the smaller asteroid. If the smaller asteroid is moving in a perpendicular direction, maybe propelled by an engine, when the cable tightens, something interesting happens.
The smaller asteroid is stopped by the cable, but the inertia of the dangerous asteroid pulls it in a third, arcing direction. This puts an arcing tug on the dangerous asteroid.
Within reason, even an asteroid that ways only a few tons could alter the direction of a much larger object.
Twenty one months ago the US was struck by an enormous ass***e and look at the damage that did.