The Sizing of Curses

Small curses are the swiftest.
Anonymous and hard to track
as rats within the walls,
invisible until they bite
and maim the child in its crib,
then fade like clouds of smoke.

Middling curses are more perilous,
more apt to betray their maker.
One false move and the shadows
can turn like dogs upon a master.
Yet fiercer they are than dogs
and faster to the throat.

Master curses are for the adept.
You must learn the arcane writ
by heart and renounce all thought
at the level of dark illumination.
You may then slay your enemies abed
and scorch their lands with light.

Curses all are cursed again.
The ones they are wrought upon
bear the edge of their harsh magic.
For ones who forge such flinty spells,
the weight of their casting
hangs and hangs within the head.

First appeared in Asimov's SF