Mindlash Sliver

Granting a sacrifice-for-discard ability to the whole tribe is a strange direction for a creature type built around stacking combat keywords, and that strangeness is the point. The discard is symmetrical, so on its surface it looks like a wash; the value comes from converting a board of expendable bodies into a stream of disruptive activations. Each Sliver becomes a Mind Rot fragment you can fire at the cost of one mana and a creature, which means a Sliver player who has run out of pressure can grind an opponent's hand to nothing one card at a time. The discard hits every player including its controller, but the deck that wants this effect is the deck that has already emptied its own hand committing to the board, so the symmetry is mostly cosmetic. It is also a sacrifice outlet by default, which quietly upgrades a wide Sliver board into something resilient against removal that wants to two-for-one: chump a swing, then trade the body for a card off the top of the opponent's grip rather than letting it sit and die. As a 1/1 for one black, the body is incidental; the card's job is to be the tribe's pressure-relief valve, the line that turns a stalled aggressive board into a slow disassembly of the opponent's resources.