Horned Sliver

Trample is the keyword that did the most for the original Sliver math. A board of identical 2/2 bodies stalls easily; opponents simply chump-block until the game grinds to a halt. The moment this hit the table, every point of excess damage carried through, and the wall of small creatures turned into a clock. Stacking the Tempest Sliver lords, each granting one keyword to the entire tribe, was how a pile of vanilla green-and-friends bodies became more dangerous than any single card on the battlefield, and trample was the conversion that made the swarm finish.

The grant is unconditional: no targeting, no restriction, so the keyword reaches your opponent's Slivers too. In the mirror that symmetry is real, but the deck was always built around being the one with the wider board, which is exactly the side that wants trample handed out for free. Later Sliver sets walked this giveaway back, gating effects behind "Slivers you control" to kill the symmetry and tighten the numbers; this comes from the era when the tribe was a genuinely communal pool, friend and foe sharing the bonuses. As a body it is forgettable, and that is the design: the chassis priced the stats low because the value lived in what the creature handed everyone else. A three-mana green creature that converts a stalled swarm into a kill is paying for the keyword, not the 2/2.