Dark Queen Tower is a time-limited tower event introduced in the update 3.5.1. Beating the tower rewards a DIAMOND character, with increased chances of Jax Briggs/Circle of Shadow, Quan Chi/Circle of Shadow and Rain/MK11.
Event duration:
1) 12/14/2021 - 02/?/2022
2) 02/25/2021 - 03/18/2022 (only Fatal)