mag-; pa-, caus.
to fall.
This stem is often reduplicated.
Don't you allow the dampness to fall [on you] so your headache won't come near [you].
Don't allow yourself to be exposed to the damp night air so that you won't get a headache.
The reason now he has a cold is because of the damp night air [falling on him] last night.
The reason he has a cold is because he was exposed to the damp night air last night.