well, first of all, what's your oppinion on this deck?

4x Brood Sliver
4x Root Sliver
4x Toxin Sliver
4x Darkheart Sliver
4x Vampiric Sliver
4x Reflex Sliver
4x Frenzy Sliver
4x Might Sliver
4x Coat of Arms
4x Damnation
4x Repopulate
11x Forest
11x Swamp

plz rate it 1-10 and revise before i build!

and, what's your favorite color/color combination deck to use? i wanna know to get some new ideas!

favorite combination R/U and U/W

6/10 sliver decks are not my favorites but i still would go b/w
ur deck is kinda straight to the point but i would add some fungus slivers, that's it,
it should be pretty efficient
some gemhide slivers may be good as well to help whith the tempo if u can get them,
if a 6 seems kinda harsh just think that most ur cards are 4+ to cast so you'll have a bit of a problem w winnie decks and control decks inspite of the root sliver. ull have at most 3 creatures by turn 5 and even w the right combination thats not too great, ull have too many cards to play by turn 4 and even thou the slivers seem like an amazing idea in theory u have to get them all in to play before they are of any use. a cryptic gateway may help as well,
4 repopulate seems redundant. and a summoners pact may be worth looking at.
good luck its an alright sliver deck.