The most recent Developer Livestream brought discussion on changes to monster health and difficulty. Going forward, World Bosses in World Tiers 3 and 4 won’t be as easy as seasons prior. It seems that the days of World Bosses being deleted in a handful of seconds will be over with the arrival of Season 4 (looking at you, Hurricane Druids).
Season 4: Loot Reborn – Developer Update Summary
World Boss Health Increase
World Boss Health has been greatly increased for World Tiers III and IV.