Barbed Sliver

Five lords anchored Tempest's Slivers, each handing the entire board a keyword or pump regardless of who controlled it; this is the one that grants firepower. The crucial wrinkle is that the bonus is not innate. It is a repeatable activated ability any Sliver can pay for, so the +1/+0 stacks as deep as your mana allows. With a wide board, the pump is shared across the team, and the open-ended cost (pay two, pump one, repeat) turns a stalled ground into a sudden kill in a way a static buff never could. The symmetry is both the catch and the character of the whole cycle: your opponent's Slivers get the ability too, which mattered when a mirrored tribal board was a real consideration. Later generations pushed the tribe toward controller-only effects (Sinew Sliver, Predatory Sliver) precisely because cards like this taught Wizards that shared keywords cut both ways. What it documents is the moment the Sliver template was still being worked out: ability-granting, fully symmetric, and built around a mana sink rather than the wide static lords the tribe eventually became known for.