Terraria/Core Keeper Crossover Monday

A post on Steam announces a crossover event between Terraria and Core Keeper begins on Monday. This will get the peanut butter in the chocolate of two extremely popular sandbox mining/construction games. Core Keeper players will be able to summon Terraria's King Slime to assist in battles, while Terraria players will gain a domesticated Caveling as a pet to share their adventures. Word is this will not be a time-limited event:
While we’ve done timed events in the past, we’re pleased to report that the Core Keeper and Terraria crossover is permanent! This means you’ll be able to summon King Slime and/or make friends with a Caveling at your leisure. This crossover comes as part of a much bigger update for Terraria too, and we hope you’ll join us in wishing the developers a huge congratulations on the update.