Browsing through the Norse part of the forums when I stumbled across this.
I always had conflicting views on making altars for specific deities, Fenrir and Jormungandr included. Typically I see two kinds of sterotypical people who work with those two: One being the Thursatru-type (and my opinion about them is pretty strong) who tend to over-emphasize the chaotic nature of both deities and only work with them in the hopes of furthering that chaotic energy in some way for some purpose (..Thursatru is dumb and makes no sense that way), and the other being people who genuinely want to work with both deities in a way that just respects their place within the universe and their purpose. I have absolutely no respect for the first group, but strong admiration and similar views as those in the second.
For someone interested in Jormungandr, or any of the primal forces within the Norse pantheon, I'd offer a bit of caution when attempting to direct their attention upon yourself. For the most part, I'd say there's a good chance you're just going to get ignored by some deities and wights (like this one) simply because they tend to not want to be involved in anything outside of their own business. If you do try to call upon the Midgard Serpent for some work, I suggest you know a lot about what you're getting into. Jormungandr is supposedly a deity that you could involve in protective work, though whether or not s/he'd actually help is up to debate. When involving Jormungandr in something, it's definitely important to recall that Jormungandr comes from Jotun-blood and the best way (in my opinion) of getting a Jotun's attention is to offer them something like blood, hard work, etc- to show you put personal effort into it. Most of the time I find that those kinds of deities aren't willing to put in effort unless you are. Making an altar for some deities, like this one, isn't always practical. But to each their own! Rant over!