Random Introductory Hero
Have you subscribed to the Marvel Heroes
newsletter? If so, you should have received an email with a Box Code that can be redeemed for five boosts and a free, randomly selected hero. (Mine was Scarlet Witch).
If you're not a subscriber yet, go subscribe so you see the next offer and simply use the Marvel Madness Gift Box Code: "MHMGIFT" to claim yours.
"Buy a Hero, Get a Hero" Promotion
If your randomly awarded hero isn't that hero you've been wanting to buy, don't sulk; you can buy a hero character this weekend and get a second (randomly selected) hero free. Mind you, that randomly selected hero might be one you've already selected (if so, you get to upgrade that hero's Ultimate Power) - and this doesn't include Dr. Strange as an option for the free hero selected, nor do you get a free hero when you purchase Dr. Strange. In fact, there are a lot of little caveats. Use the link below to check this one out fully.