http://www.wowwiki.com/Hadronox
The Pull - Start by pulling the Crusher and two elites to the side. Kill them with the party near the wall. The crushers have a knock-up effect that is mitigated somewhat by the wall surface as it won't throw you very high. This starts the entire chain of events with Hadronox. Hadronox will begin coming up through the web and takes about 2–3 minutes before he gets topside. It is considerably easier for the group to take out the two non-Elites before taking down the Crusher.
After the initial Crusher is pulled, two other Crusher groups will appear where there was only one. If you want to play it safe, pull the closest to the same spot by shooting the elite closest to the party. This will prevent the other Crusher group from coming over as well. If you prefer to get it done, just pull both groups and AOE the little elites. Tanks concentrate on the Crushers.