Sliver Legion

Legendary Creature — Sliver

All Sliver creatures get +1/+1 for each other Sliver on the battlefield.

7/7

2013-07-01:
Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn’t provide any additional benefit.
2013-07-01:
If the creature type of a Sliver changes so it’s no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures.
2021-03-19:
If Sliver Legion and two other Slivers are on the battlefield, for example, each of them gets +2/+2.
2021-03-19:
Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a Sliver may become lethal if another Sliver leaves the battlefield during that turn.