Inspired by the recent solution of the direct summand conjecture of Andre and Bhatt, we introduce perfectoid multiplier/test ideals in mixed characteristic. As an application, we obtain a uniform bound on the growth of symbolic powers in regular rings of mixed characteristic analogous to results of Ein-Lazarsfeld-Smith and Hochster-Huneke in equal characteristic. This is joint work with Karl Schwede. Speaker(s): Linquan Ma (University of Utah)