45 cards where the cards aren’t reprints and the card is tagged “sliver-stackable”

Harmonic Sliver (Time Spiral #240)
The First Sliver (Modern Horizons #200)
Sliver Legion (Future Sight #158)
Diffusion Sliver (Magic 2015 #50)
Spiteful Sliver (Modern Horizons #148)
Sinew Sliver (Planar Chaos #30)
Brood Sliver (Legions #120)
Lavabelly Sliver (Modern Horizons #207)
Predatory Sliver (Magic 2014 #189)
Muscle Sliver (Tempest #238)
Virulent Sliver (Future Sight #155)
Megantic Sliver (Magic 2014 #185)
Constricting Sliver (Magic 2015 #7)
Synapse Sliver (Legions #53)
Might Sliver (Time Spiral #205)
Essence Sliver (Legions #13)
Lazotep Sliver (Commander Masters #733)
Ward Sliver (Legions #25)
Bonesplitter Sliver (Time Spiral #149)
Cleaving Sliver (Modern Horizons #121)
Opaline Sliver (Time Spiral #244)
Sedge Sliver (Time Spiral #177)
Leeching Sliver (Magic 2015 #102)
Tempered Sliver (Modern Horizons #183)
Regal Sliver (Commander Masters #724)
Taunting Sliver (Commander Masters #727)
Thorncaster Sliver (Magic 2014 #158)
Sidewinder Sliver (Time Spiral #41)
Fungus Sliver (Time Spiral #195)
Capricious Sliver (Commander Masters #734)
Dormant Sliver (Planar Chaos #156)
Blade Sliver (Legions #88)
Battle Sliver (Magic 2014 #128)
Plated Sliver (Legions #19)
First Sliver's Chosen (Modern Horizons #9)
Mesmeric Sliver (Future Sight #53)
Spined Sliver (Stronghold #130)
Watcher Sliver (Time Spiral #45)
Lymph Sliver (Future Sight #26)
Frenzy Sliver (Future Sight #85)
Vampiric Sliver (Time Spiral #140)
Steelform Sliver (Magic 2014 #38)
Plague Sliver (Time Spiral #124)
Slivdrazi Monstrosity (Mystery Booster Playtest Cards 2019 #102)
Sliv-Mizzet, Hivemind (Mystery Booster Playtest Cards 2019 #99)

This search is finished. Now the real work can begin.