Hulkbuster is in my opinion one of my favourite Tech champions. It's appearance in The Avengers: Age of Ultron movie is already iconic: two giants, Hulkbuster and Hulk, collide in South Africa and totally wrecks the place. The Hulkbuster eventually is victorious. However, in the MCOC game, I doubt he can consistently do that. He's considered to be a "Meh Tier" champion while Hulk is a "Demi-God Tier" champion.
There are two reasons for that. Firstly, Hulkbuster suffers from being to specialised: it is decent against champions using Fury but nothing else. Secondly, Hulkbuster struggles to defeat the Hulk and the reason is that the Hulk can stun the Hulkbuster.
I suggest to make Hulkbuster immune to all bleed, poison and stun effects.
That makes sense if you think logically: its double armour should provide protection against those effects. That would expand the utility of Hulkbuster, for instant to stand against Archangel or maybe even to Thor and Drax (despite its class weakness). It would also make him unique in the game as being the first stun immune champion.
In the movie, Stark has spare parts available for him to repair Hulkbuster. Now, in the game that would be difficult but Ultron has a Self-Repair ability, so Hulkbuster could have that as well. For balancing purposes, I wouldn't make it as good as Ultron's but pretty decent: like a first 15% health recovery when going under 35% health and a second 15% health recovery when going under 15% health. That's just enough to survive a little longer but not hamper the awakened ability of Hulkbuster.
Hulkbuster could use more offence, but for that I direct you to my
Hardness ability suggestion.
I understand that the graphics team have limited time and resources, but I would find it very cool if the Heavy Attack animation was changed. Currently, it is just a dull uppercut. In the The Avengers movie, there is a moment Hulkbuster can pin down the Hulk and then starts to drill his fist in the Hulk's face. I think it would be nice if a similar animation can be used for the MCOC Hulkbuster. This is just the proverbial cherry on the top of the Hulkbuster revamp, the extra buffs are more important to me.
Let me know what you think about it!