With Marvel's upcoming comic book crossover event War of the Realms set to involve the Marvel Universe's vast library of Thor-related characters, the latest variant cover spotlights Lady Sif.

Created by Siege artist Olivier Coipel and series colorist Matthew Wilson, the variant cover for the debut issue shows Sif standing ready, her broadsword flecked with an opponent's blood. Previously, Coipel had drawn Sif in the first story arc of 2011's The Mighty Thor written by Matt Fraction.

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Next month's crossover pays off years of development in the main Thor series, as the dark elf Malekith's violent bid to rule all nine realms escalates to a full-fledged invasion of Earth.

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As the heroes of the Marvel Universe battle desperately to stave off Malekith and his fearsome allies from Jotunheim and Muspelheim, the surviving Asgardian warriors -- including Sif and Thor -- will likely lead the heroes in their last stand on Earth.

Jason Aaron and Russell Dauterman's War of the Realms #1 is scheduled to go on sale on April 3 from Marvel Comics.