The good news is that no one can beat the Hulk, and the reason that magic won’t affect him is pretty obvious to fans of the character. The two mini-series of Marvel Mech Strike depict an ongoing universe where the Avengers must battle threats. The Don Giant mech suits Captain America Black Panther and even the Hulk.
The Green Goblin and Venom use mystical energies to transform themselves into powerful monsters. The Avengers try to match Doctor Strange with a similar force. Something goes wrong and they themselves turn into uncontrollable demons.
In Mech Strike: Monster Hunters #2 The Monster Avengers by Christos Gage and Paco Diaz attack Doctor Strange, who is forced to try and restore his humanity. Strange is surprised to learn that the Hulk is not affected by that magical artifact. What happened is known as the Eye of the Kraken, which replaced the rest of the Avengers.
When Strange questions the Hulk about this, Green answers Goliath. The Eye of the Monster tries to tell the Hulk what to do but no one tells the Hulk what to do. The Hulk of all Avengers is this magical. The one who resists the curse is interesting. The Hulk is already a demon so trying to turn him into a monster is pointless.
The Hulk already has a demon mentality. Trying to rewrite his mind to become a different monster won’t work, thus making him uniquely immune to this threat. The Hulk is extremely difficult to control. What Wanda Maximoff did to her in Age of Ultron required a powerful spell.
People will forget that he was Spider-Man after Peter Parker used his magic. The Hulk reveals that he hasn’t forgotten Bruce Banner but the Hulk is not Banner. He has immunity to magic that is not on his human side. Which begs the question why Bruce isn’t immune to monster magic in the same way that the Hulk is.