out-of- pocket costs incurred in connection with such litigation or proceeding, including, without limitation, attorney's fees. RemainCo will provide prompt written notice to SpinCo, in any event no later than thirty (30) days after receipt of SpinCo's notice of its determination to initiate, prosecute and control such action or proceeding in the RemainCo Core Field, of its determination to elect to assume and pay the applicable costs or to decline to pay assume and pay the applicable costs. In the event RemainCo does not elect to assume and pay the costs associated with SpinCo's initiation, prosecution and control of such action or proceeding in the RemainCo Core Field, SpinCo shall assume and pay its and RemainCo's out-of-pocket costs incurred in connection with such litigation or proceeding undertaken by SpinCo, including, without limitation, attorney's fees. Any recovery obtained as a result of such proceeding in the RemainCo Core Field shall be retained by (i) RemainCo in the event that RemainCo assumed and paid the applicable costs of the litigation or proceeding or (ii) SpinCo in the event that SpinCo assumed and paid the applicable costs of the litigation or proceeding in accordance with this Section 8.4(b)(i). (ii) If SpinCo does not exercise its right to enforce any applicable Licensed SpinCo Intellectual Property in the RemainCo Core Field, SpinCo shall provide notice to that 20 effect to RemainCo and, as between SpinCo and RemainCo, RemainCo shall have the right to initiate, prosecute and control any action or proceeding to restrain infringement or misappropriation of such Licensed SpinCo Intellectual Property in the RemainCo Core Field. RemainCo shall provide prompt written notice to SpinCo of any determination to initiate, prosecute and control any such action or proceeding. SpinCo, as the owner and licensor, agrees to be joined as a party if necessary to prosecute