Tempered Steel (HELP)

Your deck has one win condition - overrun your opponenet by casting as many creatures as you can before they set up and boost their power/toughness with your enchantment.
Red Deck Wins and Goblins attempt to do the same thing.
Other than your magnets, however, you do not have away to remove your opponent's threats. A Red Titan, for example using a mana ramp -green or artifact, cand suddenly ruin your day as can a Day of Judgement when playing against Caw-Blade.
So you may want to include some sideboard cards to give so some 'finess" incase overrunning your opponents isn't working. A way to sacrifice a creature if it is being destroyed by a red burn spell or black destruction spell, etc. to allow you to draw cards could be added. If you block, for example, and your creature will receive lethal damage and not theirs you can sacrifice it to an artifact to draw more cards later. A way to remove your own creatures has other advantages too. What if your opponent Mind Controls or enchants one of your creatures with a painful enchantment?
Culling Dais, an uncommon from Scars of Mirrodin offers a way to replace two or three creatures for three card draws when your hand of cards is depleted. Mimic Vat is worth consideration. If they block with a Perilous Myr, for example, you can put the Myr removed from the game under the Vat and deal 2 damage to your opponent or one of her creatures once a turn. Throne of Geth allows you to sacrifice one of your artifacts so you can proliferate a Magnet to keep a nasty creature at bay (tapped to get those final points of lethal damage through. Also do not forget some of the cards the base set M11 has to offer. Steel Overseer (compare with Tempered Steel) and Valtaic Key are useful. untapping the Dais in case more than one creature is destroyed will increase your replacement card draws.
and for the next 6 months or so, Basilisk Collar, a one casting cost artifact/equipment from the Worldwake set definately needs to be in your type of deck. It equips for 2 and gives a creature lifelink and deathtouch. In matchups against red hate gaining some life can be invaluable.
Because your mana source is white you definately want the pro-red Clerics. I would main board them given so many players at FNM events are using red decks because they are inexpensive to build as well as the fact that WotC released the red Event deck (comes with two Goblin Guides!).
Finally, since your deck has no sideboard, you need to consider that aspect of your deck. In an event you can have a sideboard with exactly 15 cards or you cannot have a sideboard at all. (write down the S.B. cards - some players slip an identifier in the sleeve with the card so they can quickly remove sideboard board cards after a match before beginning a match against a new opponent. For a mirror match some form of artifact or combination of artifact/enchantment removal is needed. Do a card search for white instants and sorceries through the current Standard sets.
Three white artifact removal spells come to mind: Solemn Offering - is an instant and gains life so you can even destroy one of your own artifacts as you need to. Revoke Existance is excellent because the targeted artifact or enchantment is removed from the game - good bye Wurmcoil Engine! But it is a Sorcery. And there is Divine Offering - an instant that is cheaper to cast than Solemn Offering is by one mana (important in a low mana/ratio deck) , but the life gain becomes a variable depending on the artifact and who controls it.
The last type of card you need to consider for your sideboard or even your main deck is some type of interruption or removal. The Zendicar block offers "Oust" which deprives an opponent of a creature for two turns by placing it in their deck second from the top. It also means they don't draw another unknown threat until turn three. Excommunicate is simlar to Oust, but places the creature/card ontop of the opponent's deck. Oust is cheaper to cast than Excommunicate and so doesn't interfere with casting creature spells on your turn. Condemn is popular, but it means another turn to defeat your opponent with your army, generally, because you give your opponent extra life to be able to place the creature on the bottom of their library. Celestial Purge is powerful, but is only a sideboard card because it is limited to removing only two colors - red or black (Doesn't help with Caw-blade decks). To deal with multiple attacking creatures Dispence Justice and Choking Fumes are viable instants. I consider these to be "situational cards" because you can only cast these spells if there are creatures attacking you. If you went with the Throne of Geth to proliferate the counters on your Tumble Magnets, for example, then Choking Fumes is excellent. Neither spell targets so that is a benefit to get around prevention effects, but their draw back is that you have to keep three mana untapped from your turn to your opponent's turn - this is ok if you flood the board and empty your hand of creatures by turn 3. But on your turn three you want to play your Tempered Steel! That leaves two final cards I want to mention. Silence is cool, and can hamper your opponent's plans, especially wanting to swarm the board on a single turn or have mana ramped into playing that Titan or other nasty threat. It will be rotating out shortly and also is a rare which makes it harder to obtain. But Soul Parry is only a common. It can stop a Red Titan from dealing damage to your creatures when it comes into play and one other creature. It is excellent against "haste" decks like Vengevine, etc. It is an instant, easy to obtain, and its low casting cost will not interfere with your deck.
Having reviewed some of the alternatives my first three preferences are Revoke Existance, Soul Parry
and Condemn. After making any changes be sure to use the Vault's online deck shuffler and look at how consistent your hands are and what the next 3 or 4 draws will be. use the shuffler at least 20 times and make notes.
Good luck.
Goblinguide.