Trading Post Swamp return that card to its

return that card to its owner's hand

Fathomless descent — Return to the battlefield target nonland permanent card in your graveyard with mana value less than or equal to the number of permanent cards in your graveyard

Whenever Key to the City becomes untapped

Sacrifice another creature: Hurler Cyclops deals 1 damage to any target

Whenever one or more artifacts you control enter

Trading Post Swamp return that card to its{1}, {T}, Discard a card: You gain 4 life. {1}, {T}, Pay 1 life: Create a 0 1 white Goat creature token. {1}, {T}, Sacrifice a creature: Return target artifact card from your graveyard to your hand. {1}, {T}, Sacrifice an artifact: Draw a card.