Cautery Sliver

Most Slivers grant a passive that stacks across the board: a keyword, a stat boost, a continuous static buff every other Sliver inherits the moment it arrives. This one hands the whole tribe two activated abilities instead, and that shift reshapes what a Sliver board is for. Every Sliver becomes both a pinger and a one-damage fog, each effect costing a single generic mana plus the body of the creature pressing the button. The sacrifice clause is what keeps this from being a runaway engine: you are not amassing bodies to attack, you are banking disposable activations, so a wide board converts directly into reach or into damage prevention. The damage half turns a stalled tribal standoff into a slow clock that ignores blockers entirely; the prevention half lets you spend those same bodies as ablative armor for a player, a planeswalker, or a Sliver creature (and the prevention is strictly that, capped at the next 1 damage to a legal target). The cost is literal: you spend the permanent every time, so the go-wide-versus-go-tall tension common to the tribe becomes an accounting problem, namely how many creatures you can feed into damage before the board that generated the ability is gone. Sitting in red-white, it answers a long-running gap in how Slivers close without combat, and it does so by handing every creature in the deck an ability that was never theirs to activate.