mtg whenever a card is exiled Graveyard Trespasser | Innistrad: Midnight Hunt Foil | Standard that creature becomes a copy of a creature card exiled with Assimilation Aegis. Let the Galaxy Burn (40K)

Also from Outlaws of Thunder Junction is the "crime" mechanic, where certain cards have effects when the player commits a crime - that is, if they target opponent, a permanent an opponent controls, or a card in an opponent's graveyard, although it does lead to some very funny statements out of context

You see, whenever it attacks or becomes the target of a spell, you get to create a treasure token

Shoreline Looter Shoreline Looter is the rat version of Looter il-Kor, although one that can draw without discarding if you have threshold

Arbor Elf might essentially provide you mana, but is not a mana ability

ETBs are the meat and potatoes of these decks, and you can't take advantage of them properly without a way to return those creatures back to the graveyard