It's the only time it'll be printed, and it's a card that will likely never see its restrictions loosened up because it's simply far too good for formats to handle.
Something like the cards Ive mentioned in Standard would be a complete mess
Mardu Instants Instant (20) 1x Anguished Unmaking 1x Arcbond 1x Boros Charm 1x Cabal Ritual 1x Chaos Warp 1x Comeuppance 1x Crackling Doom 1x Dark Ritual 1x Fated Retribution 1x Fated Return 1x Gideon's Phalanx 1x Hero's Downfall 1x Increasing Vengeance 1x Kolaghan's Command 1x Leave / Chance 1x Return to Dust 1x Terminate 1x Tithe 1x Wretched Confluence Creature (7) 1x Charmbreaker Devils 1x Dualcaster Mage 1x Guttersnipe 1x Monastery Mentor 1x Thermo-Alchemist 1x Toshiro Umezawa 1x Wildfire Eternal Artifact (6) 1x Boros Signet 1x Brain in a Jar 1x Orzhov Signet 1x Pyromancer's Goggles 1x Rakdos Signet 1x Sunforger
While blue cantrips seem to be the way to go, it isnt impossible to imagine a world where access to spells like Terminate, Collective Brutality, Thoughtseize, or even Deaths Shadow create a new way to give someone the bird
Trinket Mage Trinket Mage is basically Sol Ring in a trench coat, though sometimes its Sensei's Divining Top instead
Endurance, Fury, and Solitude are the best of the bunch, though Subtlety and Grief still see some play
