FYI: Sliver Legion, Sliver Queen, and Sliver Overlord aren't Mythic rares. They are just rares. When I built my sliver deck I tried to stay away from those Slivers that had a converted mana cost of 4 or more. Plenty of good Slivers left and if you really look around you can find some good cards to go with it like the Time of Need sorcery from Kamigawa that allows you to search your library for a Legendary card and put it into your hand. Or Konda's Banner that can only be equipped to a legendary creature, but gives all creatures that share a type with it a +1/+1 and all creatures that share a color with it a +1/+1.
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Looks good, but I don't see the need for the Ameoboid Changeling or the Hive stone. There are no creatures that would benefit from those abilities.
I would consider removing Spinneret Sliver since you have Winged Slivers already in there. The abilities contradict one another and is a waste of card space. Also cut down your mana total as it looks like its making up more then half your deck and instead put in cards that will help you get that mana out quicker.
Now you have to be careful when playing with Crystalline Sliver as it will automatically cancel out any Sliver affect with the words "Target Sliver". I have one in mine and have removed all "Target" affects from the deck.
Myr Reservoir is the card and its an artifact.
Also see if you couldnt throw in a Myr Matrix. Not only does it allow you to create 1/1 Myr tokens (at a cost) it also gives all your Myrs a +1/+1. And there is a Myr land that you could look into that produces decent mana, cant remember the name right now though.