Sliver of Compleation

All Slivers gain +X/+X perpetually where X is X
plus the number of Slivers on the battlefield
{p/b}{p/b}{p/b}: All Slivers gain Deathtouch perpetually
{p/c}{c}{c}: All Slivers gain indestructible perpetually
{p/g}{p/g}{p/g}: All Slivers gain trample perpetually
{p/r}{p/r}{p/r}: All Slivers gain double strike perpetually
{p/u}{p/u}{u}: All Slivers gain unblockable perpetually
{p/w}{p/w}{p/w}: All Slivers gain vigilance perpetually