mtg whenever a card is exiled Graveyard Trespasser | Innistrad: Midnight Hunt Foil | Standard Whenever Assimilation Aegis becomes attached to a creature 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

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

Enjoy the era of Ojutai

Cards shipped protected in secure packaging

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

Jace, Cunning Castaway Jace, Cunning Castaway promises tons of looting for a proactive deck, though its other abilities are weak