I don’t suggest ranking up hulkbuster if you’re not uncollected yet. He requires the opponent to do exactly what you want to get off big damage and that’s not feasible in my content. He’s fun but not a smart rank up as your first rank 5. Also, it’s easy to get clipped when he's going in for heavies so the less fights you can do the better. It’s way smarter in your circumstance to go for havok or longshot as they’ll both do more.