Shaggy Dog, of the Winter Coat

Soulbond (You may pair this creature with
another unpaired creature when either enters
the battlefield. They remain paired for as long
as you control both of them.)
As long as Shaggy Dog is paired with another
creature, each of those creatures has "+0/+3"
If you control a Stark creature, Shaggy Dog gains
"this creature can block an additional creature"