Damn, bet I get a hero I already have and dislike
Depends on how many heroes you have. If you have less than half of the roster, chances are very much in your favour of getting someone new.
Leveling via story, do I do the actual story or just teleport to certain points and defeat a boss?
Pick up quest (some of the questgivers of the main story actually reward you XP, which is why you should always pick them up), go to the nearest waypoint, dash/teleport through the respective dungeon, beat boss, warp out, hand in quest (if required) or just move on.
I've noticed that there's a significant gap if you go from Juggernaut straight to Magneto and then into Chapter 7, since there's no other boss quests, so I tend to do that one cave you get in the first area of Chapter 6.
I do recommend doing all of the ones with bosses though, except for the one with Grim Reaper in Ch 3. That one isn't worth doing imo (and also doesn't have a waypoint in or right next to the dungeon), since you likely will be ahead of levels during the first 3-4 chapters.
I definitely recommend doing at least Sauron's Cave and maybe even the Brood-infested laboratory in Chapter 7 to catch up that rather empty Chapter 6.
If you're 40+ when you get into Chapter 8, you're pretty much good to go.
also taskmaster is straight up the lowest damaging hero in the game. maybe peoples interpretation of weakest is different, though I did mention he is survivable. His damage is so bad that nothing he has can make up for it, he does half the damage of Nova for example.
Yeah, he's utter shite, which is a big shame, because I really enjoy playing him.