Not enough slivers, no ramp if Manaweft Sliver gets killed which will likely happen. A lot of those spells are unnecessary. Slivers are going to be an aggro style, beat face and win deck. The counterspells, Cremate and Burst of Strength can all get cut, same with Enlarge and Give / Take . Jeez, same with Forced Adaptation (wayy to slow) and Primeval Bounty . Great card but not meant for this build. Also having the proper shock lands would be ideal, unless you're trying to keep it budget, but at that point it won't be getting anywhere near competitive if that's what you wanted. I would cut all the above mentioned cards, add more slivers, and more removal. That will make the deck much better. Hope that helps.

I'd maybe lose the Chromatic Lantern since you have the Manaweft Sliver 's. Maybe add Dissipate or Cyclonic Rift .

Dissolve would be good also