Slethus, Insanity's Purge

Slethus's toughness is equal to the number of lands you control.
As long as you have a creature card in your graveyard, Slethus has reach.
As long as you have an instant or sorcery card in your graveyard, Slethus has hexproof.
As long as you have an enchantment card in your graveyard, Slethus has indestructible.