Reef lobsters are not a threat to corals or other sessile invertebrates. They may prey on some ornamental worms or on small, lesser crustaceans (e.g., cleaner shrimp). You can add an Enoplometopus to a large reef tank, but you will not see it very often, unless you engage in bouts of nighttime observation. You can do this by placing a red bulb over or in front of the tank when all other lights over the tank and in the room are extinguished. They are also likely to make brief forays in the open in a larger reef tank when food is introduced. They may make brief appearances if you have a dawn-dusk transition period (e.g., a time when only actinic lights are on).
I have found the best venue to keep a reef lobster is a smaller reef tank. It is possible to keep a single specimen in a tank as small as 5.5 gallons. In a nano-reef, you will have an easier time keeping track of the lobster’s movements and thus be able to observe it with greater frequency. The decor of the smaller lobster tank should include a cave. You can strategically position a cave in your nano-reef, with the entrance facing the front of the tank so you can more easily view your reef lobster. Construct this structure out of live rock, making sure that it is deep enough (from front to back) so the lobster can hide itself completely in the shadows.