One way your opponent would try to destroy Great Maju Garzett is exposing its weak defense stat. However you can surprise them with Gamushara, inflicting a ton of damage to them and maybe even winning the duel.
Summoner of Illusions
Use Summoner of Illusions to special summon a powerful fusion monster from your extra deck which you can then use as tribute for Great Maju Garzett.
You can use Soul Exchange to get rid of your opponent's high attack monster at the same time summon Great Maju Garzett with twice that attack. To make sure your opponent has a powerful monster, you can summon Lava Golem to their field but remember that you cannot normal summon the turn you summon Lava Golem.
Here are some monsters with decent attacks that you can special summon with ease to use as tribute for Great Maju Garzett. If possible you should activate their effects before tributing into Great Maju Garzett to get the most out of them, like with Anteatereatingant and the Dark Creator.
Obviously you're supposed to summon it in Face-Up Attack Position first, then baiting the opponent by switching it into Face-Up Defense Position later on, or let your opponent use Etaqua/Econ 1st effect on it.
Then when your opponent attacked it, activate your Spikeshield with Chain you already Set beforehand.
So raw power farm deck still works in current era? All the LDs (gates or events alike) have some sort of ways to screw you. Like man eater, conclave; even the useless vehicroid deck can screw you with no entry and shield crush.
And good luck farming after putting in 5 dragons + poly + GMG (7 cards) in your sylvan/ aromage deck. I think it's highly consistent.