Defeating a boosted boss is extra lucrative. Boosted bosses contain more loot and count more kills for your Bosstiary.
Daily Boosted Boss
With every Server Save, a randomly drawn boss of the Archfoe category will receive a temporary boost until next server save. During that time, slaying the selected Archfoe will count as three kills for your Bosstiary and the boss will also carry more equipment loot than usual, with a loot rate of 250%.
Similar to the daily boosted creature, the daily boosted can be seen in the client and also on the website.