A Tarmogoyf in the yard is still a 4/5 if there are 4 different card types in the yard. So, yes, foul renewal "works"with those creatures. Their toughness is checked during resolution of foul renewal.
Death's Shadow would cause a -13/-13 effect, no matter your life total.
Characteristic-Defining Abilities, such as Tarmogoyf's P/T setting, and Lord of Extinction's P/T setting, work in all zones. Death's Shadow does not have a CDA and is simply a 13/13 in every zone except the battlefield.
604.3. Some static abilities are characteristic-defining abilities. A characteristic-defining ability conveys information about an object’s characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box). Characteristic-defining abilities function in all zones. They also function outside the game.
604.3a A static ability is a characteristic-defining ability if it meets the following criteria: (1) It defines an object’s colors, subtypes, power, or toughness; (2) it is printed on the card it affects, it was granted to the token it affects by the effect that created the token, or it was acquired by the object it affects as the result of a copy effect or text-changing effect; (3) it does not directly affect the characteristics of any other objects; (4) it is not an ability that an object grants to itself; and (5) it does not set the values of such characteristics only if certain conditions are met.
What they said, plus Foul Renewal uses the last known information of the creature card as it existed in your graveyard. So Lord of Extinction in your graveyard counts itself, and Tarmogoyf in your graveyard counts itself too if there are no other creature cards in any graveyards. Similarly, if you return a Maro with Foul Renewal, it counts the number of cards in your hand before you returned it to your hand. This is analogous with determining what a creature's power was for Fling. If you FlingLord of Extinction, it counts its power as it existed on the battlefield.
Legacy: Strawberry Shortcake, Aggro Loam, DnT+b
Modern: Devoted Karn
Vintage: Survival
Death's Shadow would cause a -13/-13 effect, no matter your life total.
Characteristic-Defining Abilities, such as Tarmogoyf's P/T setting, and Lord of Extinction's P/T setting, work in all zones. Death's Shadow does not have a CDA and is simply a 13/13 in every zone except the battlefield.
Legacy: Strawberry Shortcake, Aggro Loam, DnT+b
Modern: Devoted Karn
Vintage: Survival