Svogthos, the Restless Tomb

Oracle Text

T: Add C.

3BG: Until end of turn, Svogthos, the Restless Tomb becomes a black and green Plant Zombie creature with "This creature's power and toughness are each equal to the number of creature cards in your graveyard." It's still a land.

Card Rulings

10/1/2005 While animated, Svogthos’s power and toughness changes each time a creature card enters or leaves its controller’s graveyard.
8/1/2008 A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.
10/1/2009 Activating the ability that turns it into a creature while it’s already a creature will override any effects that set its power and/or toughness to a specific number. However, any effect that raises or lowers power and/or toughness (such as the effect created by Giant Growth, Glorious Anthem, or a +1/+1 counter) will continue to apply.