Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males must be strongly advised to practice abstinence or use an accepted and effective method of contraception ELIGIBILITY CRITERIA FOR RANDOMIZATION (STEP ): Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse during the treatment period and for weeks after the last nivolumab infusion Sexually active males and pre/perimenopausal women must agree to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study and for months after discontinuation of therapy Women of child-bearing potential and sexually active males must agree to use at least two other accepted and effective methods of contraception and/or to abstain from sexual intercourse for the duration of their participation in the study, and for at least weeks after treatment with dabrafenib or for months after dabrafenib in combination with trametinib; women of child-bearing potential must use at least two other accepted and effective methods of contraception and/or to abstain from sexual intercourse for at least months after the last dose of nivolumab and/or ipilimumab and sexually active males must use at least two other accepted and effective methods of contraception and/or abstain from sexual intercourse for at least months after the last dose of nivolumab and/or ipilimumab; should a woman become pregnant or suspect she is pregnant while she is participating in this study, she should inform her treating physician immediately Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study and until days from the last study treatment Sexually active males must use an accepted and effective method of double barrier contraception or abstain from sexual intercourse for the duration of their participation in the study and for weeks after the last dose of study drug Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study and for months post rituximab treatment Women of childbearing potential and sexually active males must be strongly advised to use accepted and effective methods of contraception, as described in the informed consent form (ICF), or to abstain from sexual intercourse for the duration of their participation in the study; women of childbearing potential should use adequate methods to avoid pregnancy for weeks after the last dose of nivolumab; sexually active males should use adequate methods to avoid pregnancy for weeks after the last dose of nivolumab Patients must not be pregnant or breastfeeding; sexually active patients are strongly advised to use accepted, effective forms of contraception Women of child-bearing potential must use at least two accepted and effective methods of contraception and/or to abstain from sexual intercourse for at least months ( days) after the last dose of nivolumab and/or ipilimumab; sexually active males must also use at least two accepted and effective methods of contraception and/or to abstain from sexual intercourse for at least months ( days) after the last dose of nivolumab and/or ipilimumab Women of child bearing potential and sexually active males must use an accepted and effective non-hormonal method of contraception Women of child-bearing potential and sexually active males must use an accepted and effective method of birth control Pregnant women may not participate; women of childbearing potential and sexually active males will be advised to effective contraception while on study Pregnant women may not participate; women of childbearing potential and sexually active males will be advised to use effective contraception while on study Sexually active males must be strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for at least one week prior to the start of the research study, and continuing for months for women of childbearing potential and months for sexually active males after the last dose of the study drugs Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception PHASE II: Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must use an accepted and effective method of contraception or agree to abstain from sexual intercourse during their participation in the study and for months following completion of their participation Women of childbearing potential and sexually active males must use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males are strongly advised to use appropriate contraceptive measures Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for days after the last dose of study drug Women of childbearing potential and sexually active males are strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of non-hormonal contraception; acceptable contraception includes barrier methods (e.g., condoms or diaphragm) or intrauterine devices or IUDs (these may include low-dose hormones at the discretion of the Study Chair) Women of childbearing potential and sexually active males are strongly advised to use an accepted and effective method of contraception Women of childbearing potential and sexually active males must be strongly advised to use an accepted method of contraception Women of childbearing potential must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the following year until the year AB-MR and DBT studies are performed Women of childbearing potential and sexually active males must use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males are strongly advised to use an accepted and effective method of contraception Women of childbearing potential must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study Women of childbearing potential and sexually active males must be strongly advised to use an accepted and effective method of contraception or to abstain from sexual intercourse for the duration of their participation in the study