World of Overwatch - PvE RPG Grind Mode v2.6.1 (by Delwion#2667):
1-6 players must defeat regular enemies, champions, and bosses to earn XP! With every additional level, players get more powerful and gain a certain amount of Ability Points they can spend on useful passive abilities. But enemies get stronger as well. Choose your preferred hunting zone (difficulty) and grind your way up to the highest levels. Will you have the time and skill it takes to beat the legendary level 100 boss in 90 minutes?
Full details posted on official forums (very long post):
Most important instructions:
Inside the Hearthstone tavern, press Crouch near an ability icon to gain a level in that ability.
Use Need healing outside of the tavern, to cast a town portal spell.
Team 2: 1-6 Players