WoWDB

Oondasta is a rare spawn world boss on the Isle of Giants.

As of a hotfix today, Oondasta's health has been reduced by 50% (to 436m). Yes, you read that right. The short of it is that Oondasta hadn't intended to be zerged, but that's what players were doing and it consistently led to server instability because so many players were in one place. Blizzard decided that it'd be better to nerf Oondasta's HP (so smaller groups would have a higher chance of success) rather than allow a significant decay in gameplay experience in general to continue. (Source)

From the Patch 5.3 PTR Notes:

Oondasta

• Shiny Pile of Refuse now has a chance to contain a Primal Egg, and a number of Dinosaur Bones.
• Spitfire Beam no longer increases in damage with each jump, deals a flat 200,000 damage(up from 150,000 damage), and jumps to 99 targets (up from 20 targets).

Oondasta's health pool was nerfed by 50% (not currently reflected by the Quick Info box). Reasons for the nerf.