he city-plane of Ravnica is full of guilds. And it's also full of guild symbols. And from that it follows that Gatecrash, being set on Ravnica, has guild symbols in card art.
Sometimes, the symbol is prominent, in the fashion of the Boros Truefire Paladin.
Truefire Paladin | Art by Michael C. Hayes
Sometimes, they're being formed out of pure magic, like the Simic symbol on Gyre Sage.
Gyre Sage | Art by Tyler Jacobson
Sometimes they're hidden, like the Gruul graffiti on the wall next to Wasteland Viper.
Wasteland Viper | Art by Lucas Graciano
Sometimes it's chiseled on the wall of an Orzhov mausoleum, as on Immortal Servitude.
Immortal Servitude | Art by Seb McKinnon
Sometimes they're graffiti on a person! Wait, that's just a Dimir tattoo. Anyway, here's Coerced Confession.
Coerced Confession | Art by Mathias Kollros
Monty Ashley has worked at Wizards of the Coast since 1997. He writes the Arcana and Card of the Day features along with planning the expansion-specific minisites.