Katrina - WRG Slivers
 
Creatures:
1 Battering Sliver
1 Bonesplitter Sliver
1 Cautery Sliver
2 Druid of the Anima
1 Fungus Sliver
4 Gemhide Sliver
1 Heart Sliver
4 Homing Sliver
3 Lymph Sliver
2 Muscle Sliver
1 Poultice Sliver
2 Reflex Sliver
4 Sidewinder Sliver
3 Sinew Sliver
2 Sliver Legion <3
3 Two-Headed Sliver
4 Virulent Sliver
Total: 39
 
Spells:
1 Reins of the Vinesteed (Enchantment)
2 Stream of Life (Sorcery)
1 Spore Cloud (Instant)
2 Tranquility (Sorcery)
Total: 6
 
Land:
5 Plains
10 Forest
7 Mountain
Total: 22
Total Cards:67
 
Alright, here's the deal: I am not necessarily new to the game of Magic, but that doesn't mean I know every single card that makes the game. In fact, my friend basically gave me this deck, and I bought a few more. The problem is that I am getting CONSTANTLY bulldozed by other decks, and ones that aren't necessarily tournament competitors, either! So basically I'm tired of being the chick to beat for a confidence booster, and I would also like to get a few tournaments under my belt. I don't even have to win, I just want to be a force to be reckoned with! PLEASE HELP!!!!
 
Good ol' slivers. I actually designed a deck similar to this for my friend and I'm a fan of slivers myself so this should be a good fix. Firstly, total card count: 67, too high. Always always run 60 cards. The more cards over 60 that you run reduces to chance of drawing any individual card, thus you want to ensure you run high quality cards with the best chance of drawing those cards. Now individual card choices:
 

• Gemhide is a nice card, allows you to both mana fix and ramp so it stays
• Sinew and muscle are both nice early beaters that still power up your late game
• Lymph is interesting, in multiples it can become very annoying and even by itself it plays with combat math, when I've used it I haven't been disappointed.

What to cut -

• Firstly I'm going to suggest cutting all the red out, it doesn't really bring much to the deck, cutting it smoothes your mana and lets you add better cards
• Virulent Sliver, this was good in 2HG TSP because you could suddenly surprise your opponent with a rush of slivers. this isnt as likely to happen here, especially if your playing multiplayer. Secondly unless you get it out early it doesnt make a much of an impact. I say this because if you have enough slivers to make it worthwhile you can probably win through damage. On the other hand I can see how it would be useful, I personally however wouldn't use it.
• Spore Cloud, your playing an aggressive deck and don't want to be wasting time
• Stream Of Life, a sub-par card at the best of times, this similar to the last card definatly has no place in an aggressive deck.
• Reins of the Vinesteed, true it does have the ability to recur itself but in this case rancor is a much better option, granting trample as well and still allowing it to come back after mass removal.

What to add -

• Congregation At Dawn, this makes an excellent, if not better replacement for homing sliver, allowing you to run singleton slivers and still effectivly search them out.
• Pulmonic Sliver, ABSOLUTE must have for any sliver deck with W in it. Serves an excellent counter to mass removal, the bane of sliver decks for a long time. It can easily replace Poultice Sliver. Add in to the fact that this is an optional ability and it becomes even better (if the ability was mandatory then it could deny you vital draw steps)
• Might Sliver, provides a nice boost
• Victal Sliver, interesting, if your creature is going to die anyway it provides a decent life boost and can also allow for a mini combo with pulmonic.
• Oblivion Ring, excellent card and all purpose removal, perfect for an aggro deck.
• Ajani Goldmane, possible, it pumps your creates and allows them to stay back on defence that turn, so overall not bad
• Essence Sliver, another absolute must. This thing is so insane it is not funny. Lets say you have pulmonic, might and essence (not unheard of), swing for 14 in the air, I gain 14? Not bad.
• Ward sliver, another very nice card. Protection from your team and removal? Why not?
• Harmonic Sliver, maybe a 1-of that allows you to deal with troublesome artifacts and enchanments
• Quick Sliver, Allows to play surpise attackers (play at the end of your opponent turn) and blockers

 
Well I hope I've helped, I'll be getting round to some more lists soon