mtg duskmourn commander deck Magic The Gathering (4) cunning tricks Magic: The Gathering - Duskmourn:

Whenever Phyrexian Obliterator receives damage, the person who did it has to sacrifice that many permanents

It even works for planeswalkers and their ultimate abilities

Also special mention goes to Chromatic Lantern

16 The Return Of Hercules Card 215/204 EN.7, Emerald Ink Although the benefit of the Action card, "The Return of Hercules" is a risky one by allowing every player to immediately play a character card from their hand for free, this Enchanted version of the card is a stunning work of art

UW Reanimator players are going to love this little engine

Grist, The Hunger Tide: An extremely unique planeswalker that's also a tiny insect