As noted many times, there’s quite a bit to grind out in Marvel’s Avengers. You have to gear up each of the six heroes separately and that’s not including the Challenge Cards full of cosmetics to blow through. But how do you fully level a hero and unlock all of their abilities? Where do you possibly get that much XP?
First off, finish the campaign since it will give XP for all heroes and allows you trial each one to find a favorite. Once that’s done, pick a hero you like and focus on them. Black Widow and Captain America are recommended for more quick, brawling-type heroes. They’re also fairly powerful especially if you achieve 100 percent uptime on Veil of Shadows/Power Surge and Brooklyn Brawler respectively.
In the end-game, there’s lots of different content to go through but you want to balance time spent with XP earned. To that end, HARM Rooms are the best option. They take place in a single space and require you to take down multiple enemies. Drop Zones are second best and usually take a few minutes. They’re best for farming resources in addition to XP over a short period of time (and can also help in gearing up a hero).
It’s worth leveling and gearing up different heroes since their loadouts will be used whenever playing with AI companions. Just remember that AI companions won’t earn XP during these missions – you need to level up each hero separately on your own.