Study of Magrolimab Combinations in Participants With Myeloid Malignancies

The anti-leukemia therapies are defined as follows: * Venetoclax (Ven) * Azacitidine (Aza) * Mitoxantrone, etoposide, and cytarabine (MEC) This study consists of 3 safety run-in cohorts; * Safety Run-in Cohort 1 (1L Unfit AML Mag + Ven + Aza) * Safety Run-in Cohort 2 (R/R AML Mag + MEC) * Safety Run-in Cohort 3 (Post-chemo Maintenance Mag + CC-486) Participants will receive treatment at the assigned dose level for at least 4 cycles in the Safety Run-in cohorts, after which they may continue at the assigned dose level or switch to the RP2D upon agreement between the investigator and the sponsor. After completion of each safety run-in cohort and identification of the RP2D for that cohort, participants may be enrolled into the corresponding Phase 2 cohorts; * Phase 2 Cohort 1 (1L Unfit AML Mag + Ven + Aza) * Phase 2 Cohort 2 (R/R AML Mag + MEC) * Phase 2 Cohort 3 (Post-chemo Maintenance Mag + CC-486) Cycle length is 28 days for both the Safety Run-in and Phase 2 cohorts. Note: All cohorts are closed to screening and enrollment.