Once the last few slivers the Riptide Project controlled were dead, there was nothing to keep the island from being completely overrun.

Shifting Sliver

Slivers can't be blocked except by Slivers.

The List

Commander Masters

Legions

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.

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.