Astrophysical transients are discovered by optical time-domain surveys in unprecedented numbers, with >20,000 new events in 2023 alone. This rate will grow exponentially as the Vera C. Rubin Observatory begins its 10 year Legacy Survey of Space and Time. LS4 will enhance this science by conducting an extragalactic transient survey using a unique g+i+z filter pattern capable of observing ∼9000 sq. deg. per night to a depth of ∼21 mag.  From these data, LS4 will provide unique constraints on young extragalactic transients discovered within days of explosion, populations of rare transients in the local Universe such as extreme supernovae, black hole-driven and more exotic transients, and probe the unique population of redder optical transients with LS4’s filter pattern and red sensitive CCDs.