Summoners War, by Com2uS Corp., is getting guild battles in its newest update. Every week, Guild Leaders or Vice Leaders can initiate guild battles that will be auto-matched against opponents based on their guild points. The 2 round battles are 3v3 match-ups, where players use a team of 6 monsters to fight. During the fight, you'll be able to choose 3 monsters to defend instead of fighting. Every time you win, you'll get guild points and guild experience based on the strength of your opponent. The update also introduces a bunch of new characters called Ice Warriors, as well as added fusion recipes.
You can join the fight by downloading Summoners War for free on the App Store.