This boss is mainly a straightforward fight. When he summons spores, melee dps, and maybe 1 mage should burn them down ASAP. Loatheb will casta spell every 20 seconds for 17 seconds that will prevent all healing from being done. This means that healers will only have 3-4 seconds to heal tanks (assuming that u start healing 1 sec. beofre spell is over). On Heroic difficulty, he has a little under 21 million health.