Ogres are modified thralls. Tortured and fed up till they transform in those things. What if one Thrall didn't turn in an abomination? What if the Hive experiments succeeded? Thralls are deadly in packs, just look at the Abyss. Even though they are easily one-shotted, they can take you down before you reload. Now imagine... all those Thrall in the Abyss. 5 times the size, speed and strength of a normal Thrall. Cursed as well. Not even all Guardians combined can stop that force. That's why we must destroy Bob, the Perfect Thrall!