Some of these can still be played in your MTG Arena decks, though several have also done time on an MTG banlist or two
With a card like this you can't just be cruel, you gotta get ruthless
Contents: 1x Halo Foil Higure, the Still Wind, 1x Halo Foil Nezahal, Primal Tide, 1x Halo Foil Dragonlord Kolaghan, 1x Halo Foil Mina and Denn, Wildborn, 1x Halo Foil Xantcha, Sleeper Agent
Paradoxically, it may fit best in decks with a heavy investment in green ramp spells to maximize the number of charge counters obtained each turn
Stromkirk Occultist, and Call to the Netherworld are examples of really good options with madness that result in card advantage