With these 4 monsters together, they can be used interchangeably to either make 1 strong monster, or 3 level 4s on the field. Since the lower level magnet monsters are normal monsters, they are useful in a normal monster deck. The problem though, is with the smaller monster zone in Duel Links, Valkyrion the Magna Warrior can only activate it's ability when you have no other monster on the field, making it much less flexible.
When Beta The Electromagnet Warrior is summoned, you can add a low-leveled Magnet Warrior monster from your deck to hand. Then you can tribute him during your opponent's turn to special summon another low-leveled Magnet Warrior monster from your deck.
Painful Decision simultaneously mills a normal monster from your deck and adds a monster with the same name to your hand, making it a very efficient card in this deck.
Xing Zhen Hu is effective for disturbing your opponent's strategies, it forces them to play their backrow early or have it locked in place. It is best to activate this before you bring out your powerful monsters just to be safe.
If you have a lot of Rock-type monsters in your graveyard, remove them to special summon Megarock Dragon. His attack and defense will be equal to the number of Rock-type monsters you removed form play to summon him.
You can special summon Valkyrion the Magna Warrior (Must first be special summoned using the required condition) after successfully using its effect to fill the board with your Magnet warriors (Normal monsters).
Since magnet warriors are normal monsters this card can be use in some situations. Just be mindful that your warriors are needed in your side of the field or in your hand to summon Valkyrion the Magna Warrior.
+2 ECON, -1 Delta +1 Dust Warrior (use Dust Warrior to trigger Deltas graveyard effect from the deck, or send your second or third Magnet to the graveyard to Normal Summon Delta for an ECON tribute) -1 Sorc Wall, -1 Interdim Transporter, -1 Atk The Moon, +1 Valk from Yugi Muto level up, if you have it +2 Dimension Gate to synergize with ECON tributes to potentially steal monsters whensummoning Val
I agree on everything he said except the last three, attack the moon can really help with disrupting your opponent's plays by forcing them to either play their backrow early or to loss it. If you get val out, you can simply play patiently while your opponent losses their resources. If you have 2 or more val then you're going to brick more often as this decks main goal is to summon via delta.
If you add the dimensional gates just for the purpose of stealing via econ take, then you're going to either be waiting on those set cards and not focusing on summoning val or you're going to draw into them at a top deck situation where a more defensive backrow would have been more useful.
I've managed to make Legend 3 with my magnet warrior deck a few times. Got knocked back down due to some bad luck and disconnections. Magnet warrior decks are so underappreciated, and if used properly, can counter a vast majority of meta decks.