The hostile mobs in the trovian adventure world do all have a different amount of health and damage, depending on the kind of mob and the world-tier. Higher tiers causes stronger enemies. Also, enemies have more health in the following order: Minimobs, ranged mobs, melee mobs, bosses.
The following tables should give some insights.
Note: The numbers marked with (*) exceed 34608, so they are achieved through several added shots. These numbers aren't guaranteed to be correct.
Sky Realm / Radiant Giants
First tries on Radiant Giants took 156 hits at 17968 damage per hit. So the health is about 2,8 million*.