Jaggedly is how something happens, or how a line runs, when it is not smooth: in a rough, pointed, stop-and-start way. A cliff may drop jaggedly to the water; a cut may run jaggedly across the page; after a shock, a person may breathe jaggedly, in uneven gulps rather than a steady stream. It is simply jagged plus -ly, so it wants a verb or a picture of manner. In easy speech many people skip the adverb and say “in a jagged line” instead; the -ly word is a little less common, but it is the one that belongs beside a verb.