Legends of Runeterra: The Shadow Isles is a new regional card set. The Shadow Isles card set is based off of the region with the same name that is clouded by a black mist that has tainted the land and corrupted the isles.
League of Legends champions come from this region, but only four have made it into Legends of Runeterra in Elise (2-cost), Kalista (3-cost), Thresh (5-cost), and Hecarim (6-cost).
Legends of Runeterra: Shadow Isles' Theme
These decks will be the first and only set in the game to feature "Kill an Ally", "Drain", and "Steal" card abilities. Decks with these cards will focus primarily on sacrificing your own cards for later power and will become incredibly dangerous towards the later stages of the game.
Defeating Shadow Isles decks will require plenty of early damage to stop them from snowballing and getting their dangerous combos off. A full list of the Shadow Isles cards is here.