Magic Monsters a'gatherin'

[Owrtho]

true, but the first edition sliver card had 4 limbs, and that's what I based it off

There are no slivers in first edition. That said, if by first edition you mean the first set with slivers, that would be Tempest. However, in Tempest all slivers (save Mnemonic Sliver, Muscle Sliver, and Winged Sliver) are clearly shown to have only one limb and double tails. The Mnemonic sliver varies only in it not being clear (the picture focuses on the head), Muscle Sliver looks to have two arms, and the winged sliver has wings as well as looking to have two arms.

The closest looking picture to a sliver with 4 limbs is the Crystalline Sliver from stronghold, though even there if you look it just has its twin tails wrapped around a pillar and still only has one arm (the head is obscuring where a second arm would likely go, but if one look closely they'll see there is no second arm).

The only other slivers that seem to have more than one arm are Sliver Queen, Sliver Queen Avatar, Sliver Queen, Brood mother, Sliver Overlord, Two-Headed Sliver, and arguably Sliver Legion (though it seems to be more a large group of slivers than one with multiple limbs).

Owrtho