• Age \>/= 18 years

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2

• History of one of the following histologically documented hematologic malignancies that are expected to express the CD20 antigen: In the Dose Escalation phase, participants must have relapsed after or failed to respond to at least two prior lines of systemic therapy. In the Dose Expansion phase, participants with FL Grades 1-3a must have relapsed after or failed to respond to at least one prior line of systemic therapy and must require systemic therapy. Participants with DLBCL/transformed FL must have relapsed after or failed to respond to at least one prior systemic treatment regimen.

• Participants with DLBCL/transformed FL who have received only one prior line of therapy must: Not be considered a candidate for autologous stem cell transplantation (ASCT) due to age, performance status, comorbidities and/or insufficient response to prior treatment, or have refused ASCT; or be ineligible for or unable to receive chimeric antigen receptor T-cell (CAR-T) therapy due to reasons defined by the protocol

• Fluorodeoxyglucose-avid lymphoma (i.e. PET-positive lymphoma)

• At least one bi-dimensionally measurable nodal lesion (\> 1.5 cm in its largest dimension by diagnostic quality CT or PET/CT scan), or at least one bi-dimensionally measurable extranodal lesion (\> 1.0 cm in its largest dimension by diagnostic quality CT or PET/CT scan)

• Availability of a representative tumor specimen and the corresponding pathology report for confirmation of the diagnosis of NHL

• A fresh pretreatment biopsy during screening period, excisional or incisional, is preferred

• Adequate hematologic function without growth factors or blood product transfusion within 14 days of first dose of study drug administration

• Normal laboratory values

• All participants and health care providers will be trained and counseled on pregnancy prevention. For female participants of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use contraception during the treatment period and for 3 months after the final dose of mosunetuzumab, at least 18 months after pre-treatment with obinutuzumab or 2 months after the last dose of glofitamab, 28 days after the last dose of CC-220, 28 days after the last dose of CC-99282, 3 months after the last dose of tocilizumab (if applicable), whichever is longer

• For male participants: agreement to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agree to refrain from donating sperm during the treatment period and for at least 3 months after pre-treatment with obinutuzumab or 2 months after the last dose of glofitamab, 28 days after the last dose of CC-220, 28 days after the last dose of CC- 99282, 2 months after the final dose of tocilizumab (if applicable), whichever is longer