I am running with a deck similiar and i think you will find the biggest weakness is easy removal. I would add Boros Charm and Selesnya Charm to the mainboard and maybe Ranger's Guile in the sideboard. Other than that Mutavault is a solid land for this deck.

Simic Charm ***

This is the Sliver deck I made and am using and seems to go really well so far Sexual Predators (Slivers featuring Aurelia). As for the Lanturnand Darksteel Ingot manaweft does all the mana fixing so you should be fine.

You definitely need together rid of the four extra cards. I would reduce the Megantic Sliver to 2ish as you should be winning before you can play them easily anyways. Clone might work but Progenitor Mimic is definitely too slow for the deck. You dont need 4 Striking Sliver or any Steelform Sliver at all. You could also do with an extra two or so lands.

I have a sliver deck also idc/idk if you care to look but here is link. http://tappedout.net/mtg-decks/sliver-swarm-12-08-13-1/It isn't perfect but it does work fairly efficiently.

I wouldn't run Steelform Sliver and it's not necesary to splash black for Syphon Sliver . Hive Stirrings is sorcery speed, and depends on other slivers. I wouldn't run it unless I included Rootborn Defenses and Advent of the Wurm for better synergy. To be honest, Lay of the Land is holding space. You don't need Verdant Haven if you are running Manaweft Sliver . Instead of running Darksteel Ingot , why not go for three Chromatic Lantern ? Door of Destinies is slow and won't work right away. Don't run guildgates... they are too slow and can quickly become a burden. Try Shimmering Grotto or Transguild Promenade . Consider using Shock , Boros Charm and/or Ready / Willing .

Fix that sideboard... Groundshaker Sliver is terrible and Battle Sliver can't be relied on. Fog and Massive Raid are very specific. You could try running Simic Charm , Selesnya Charm , Savage Summoning , and perhaps Detention Sphere .

1+. for the attempt. Perhaps you could take a look at my bant sliver deck, Slivers are on a running riot!, to get some ideas since I run three of your colors.

Thank you all for the great feedback!

I'll start with the land issues: I DEFINITELY am removing the guildgates and replacing them with shock land such as Shimmering Grotto , I forgot to mention that in the description but it is a for sure goal in my deck, just a pricey one at that. Now to Manaweft Sliver ... I've actually found I'm not pulling these as much as I would like, even with a full playset of 4. Verdant Haven just supplements this, but I think scaling it down to just 2 and taking out Into the Wilds would be fine. I eventually want to replace Darksteel Ingot with x2 Chromatic Lantern . Lay of the Land is actually an old card I had before putting in guildgates to solve the wrong color mana problem. These will probably be removed.

Now to the various charms: Thanks for the awesome idea! I didn't really think of charms in this deck but they're a really good enhancement. I have a few Boros Charm and Simic Charm already and will update the deck shortly. That has been a problem in Friday night Magic tournaments for me against red decks... the fact my creatures can just be shot down. I will probably run x2 of each charm and x2 Ranger's Guile in the sideboard for when I'm up against a straight red burn deck (easily a counter to this deck at the moment).

As for the sideboard: Ya the sideboard is NOT done. I was just showing what extra sliver options I had, although pretty much all of them are useless. My fault, should have put them in the maybeboard instead of the sideboard.

Now to the creatures: Battle Sliver and Groundshaker Sliver are indeed pretty useless when I have Megantic Sliver and Bonescythe Sliver . Steelform Sliver has saved me a few times but I may remove all of them just to slim down the deck a bit. Syphon Sliver I think I will keep in the deck for now. I don't have nor do I need swamps or black mana in the deck for it, since there are so many "tap for any color" options in the deck already. Clone is nice, but Progenitor Mimic is too slow, I agree now that I've tested with it.

Thanks again for the feedback, I know I didn't get to everything in this comment but I'll update the deck and comment again shortly!

Sorry didn't mean to call Shimmering Grotto shock land! XD

What's the popular opinion on adding Mutavault into the deck? I've heard some opinions rave about them saying it would be awesome to include while the other side says it's not worth using the land.

Mutavault is a very, very important card on the deck. The most popular opinion about it is that a sliver deck "should include four of them", which I consider to be dumb because it could potentially damage your draw and opening hand. Two or three of them are fine.

I'll probably add 2x Mutavault in to not make my deck too big with the Boros Charm and Simic Charm additions. I'm also taking out Hive Stirrings as I find myself only using it to have throw away blockers, which doesn't make sense when I can play a much more powerful creature for that same mana cost.