Sliver Upgrade Kit
A collection of 35 powerful new cards to take your Sliver deck to the next level.
Mana rocks help stabilize your manabase and allow you to cast your spells sooner. Beating your opponents to the punch is always beneficial.
Scry lands allow you to smooth your draws, this lets you fix a bad starting hand or in the later game lets you draw more of what you need and less of what you don't.
Many of these creatures give all of your slivers new abilities. Some give flying, deathtouch, +1/+1 counters, hexproof, double strike, vigilance, haste, mana generation, sacrifice abilities, etc.. There are too many synergies to get down in one paragraph.