Dave Guskin, Game and Design Director for Runefield, discussed how League of Legends champions are adapted into characters and decks for the trading card game. He explained that the team first identifies the most recognizable traits of each champion, then attempts to represent them through card mechanics. Skills don't need to be copied one-to-one; what matters is whether the adaptation creates engaging gameplay.
Take Ezreal as an example: the team sought to translate his rapid movement and teleportation feel from League of Legends into the ability to swiftly traverse different battlefields in Runefield. Guskin noted that such designs still need playtesting to determine if they're fun.
Darius's execute ability underwent a different set of adjustments. The team initially tried applying this effect to champion units, but its repeated use proved frustrating for opponents, so they ultimately incorporated the execute mechanic into his exclusive spell.
Guskin considers Rengar a successful adaptation. Rather than directly porting one of his abilities, Runefield uses an ambush mechanic to create pressure, making opponents feel the threat of a sudden attack.