This version of Gem-Knight, designed to go first, works because of Crystal Rose; it's been used in Master Duel for a while now, along with Fiendsmith.
The idea is that Crystal Rose can be accessed through any engine that can cast LINK-2 Spright Spring on the field and put a Fusion Monster in the GY. Fiendsmith does this with the Lacrima Fusion Monster; in this Magnet Warrior deck, you use Plasma Magnum instead.
Below, I'll show four combos and test hands as well. The deck itself is very interesting because you have a total of 21 one-card combos, use 18 tech cards, and create the best possible endboard for current Yu-Gi-Oh!: it separates interactions into different locations.
You have monster effects on the field, in your hand, and in the GY. With this, it's practically impossible for your opponent to break your field with board breakers, much less achieve an OTK (One Turn Kill).
And the deck's follow-up is good too because you can return monsters from the main deck and extra deck to summon them again and easily OTK (One Turn Kill).
You can recycle all the Rock monsters like Gallant Granite, Plasma Magnum, Flux, and the LINK-2 Gem-Knight Phantom Quartz, as well as the Gem-Knight Seraphinite fusion, not to mention that Gem-Knight Master Diamond Dispersion can summon both the fusions back to the field and Nepyrim from the GY.
The deck has good consistency; sometimes you draw cards that force you to play unorthodoxly. The Magnet Warrior engine is reduced, removing unnecessary one-off cards in this version.
One advantage of the Magnet Warrior cards is that they play well against high-impact hand traps, for example, Droll&Lock Bird and especially Mulcharmy Fuwallos and Purulia.
---------------------------------Combos:
The idea is that you can always get through with Nepyrim, Orange Light, and Green Light in hand, which by itself guarantees you win most games, not to mention cards like Flux, Telllusion, I:P making S:P, A Bao bringing Diviner back to send Mudora to the GY, and Hollowcore omni negate.
In some combos you need to normal summon Nepyrim to reach Gallant Granite and access Magnet Warrior's engine, but if you already have access to Linear Magnum, or even have a Mulcharmy in hand, you may not need to use Nepyrim to continue the combo and can leave her in your hand.
Combo 1: Nepyrim + 1 discard (full combo)
https://www.duelingbook.com/replay?id=686678-80681149
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux /in GY: 2x Hollowcore (omni negate) + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Nepyrim + Orange Light + Green Light
Combo 2: Linear Magnum/Bonding + 1 discard
https://www.duelingbook.com/replay?id=686678-80705123
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux + Gigantic Spright /in GY: Hollowcore + Mudora + Diviner + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Nepyrim (Add Orange Light or Green Light)
Combo 3: Beta + 1 discard
https://www.duelingbook.com/replay?id=686678-80706666
End Board: A Bao + I:P + Tellusion + Lady Rose + Gigantic Spright /in GY: Hollowcore + Mudora + Crystal Rose + Diviner /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Nepyrim (Add Orange Light and Green Light on Opponents turn)
Combo 4: Dispersion + 1 discard
https://www.duelingbook.com/replay?id=686678-80732730
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux /in GY: Hollowcore + Diviner (send Mudora) + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Orange Light + Green Light
Combo 5: Crystal Rose + 1 discard
https://www.duelingbook.com/replay?id=686678-80760856
End Board: A Bao + Tellusion + Lady Rose + Flux /in GY: Hollowcore + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Nepyrim + Orange Light + Green Light
Combo 6: Diviner + 1 discard
https://www.duelingbook.com/replay?id=686678-81047563
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux /in GY: Diviner (send Eva) + 2x Hollowcore (omni negate) + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Nepyrim (add Orange Light and Green Light)
Combo 7: Armadillo + 1 discard
https://www.duelingbook.com/replay?id=686678-80734607
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux /in GY: Diviner (send Mudora) + Hollowcore + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Orange Light + Green Light
Combo 8: Brilliant Fusion + 1 discard
https://www.duelingbook.com/replay?id=686678-80735355
End Board: A Bao + I:P + Tellusion + Lady Rose + Flux /in GY: Diviner (send Mudora) + 2x Hollowcore (omni negate) + Crystal Rose /Banished: Sigma Minus + Sigma Plus /in Hand: Gem-Knight Fusion + Orange Light + Green Light
---------------------------------