POWER OF ATTORNEY
             FOR EXECUTING FORM ID, FORMS 3, FORMS 4 AND FORMS 5,
                   FORM 144 AND SCHEDULE 13D AND SCHEDULE 13G

The undersigned hereby constitutes and appoints Christopher Stavros, Joan
Gallagher, Carlton Ellis and Timothy D. Yang, or any of them acting without the
other, with full power of substitution, as the undersigned's true and lawful
attorney-in-fact to:

      (1)   Execute for and on behalf of the undersigned a Form ID (including
            amendments thereto), or any other forms prescribed by the Securities
            and Exchange Commission, that may be necessary to obtain codes and
            passwords enabling the undersigned to make electronic filings with
            the Securities and Exchange Commission of the forms referenced in
            clause (2) below;

      (2)   Execute for and on behalf of the undersigned any (a) Form 3, Form 4
            and Form 5 (including amendments thereto) in accordance with Section
            16(a) of the Securities Exchange Act of 1934, as amended (the
            "Exchange Act"), and the rules thereunder, (b) Form 144 (including
            amendments thereto) and (c) Schedule 13D and Schedule 13G (including
            amendments thereto) in accordance with Sections 13(d) and 13(g) of
            the Exchange Act, but only to the extent each form or schedule
            relates to the undersigned's beneficial ownership of securities of
            Magnolia Oil & Gas Corporation, or any of its subsidiaries;

      (3)   Do and perform any and all acts for and on behalf of the undersigned
            that may be necessary or desirable to complete and execute any Form
            ID, Form 3, Form 4, Form 5, Form 144, Schedule 13D or Schedule 13G
            (including amendments thereto) and timely file the forms or
            schedules with the Securities and Exchange Commission and any stock
            exchange or quotation system, self-regulatory association or any
            other authority, and provide a copy as required by law or advisable
            to such persons as the attorney-in-fact deems appropriate; and

      (4)   Take any other action in connection with the foregoing that, in the
            opinion of the attorney-in-fact, may be of benefit to, in the best
            interest of or legally required of the undersigned, it being
            understood that the documents executed by the attorney- in-fact on
            behalf of the undersigned pursuant to this Power of Attorney shall
            be in the form and shall contain the terms and conditions as the
            attorney-in-fact may approve in the attorney-in-fact's discretion.

The undersigned hereby grants to the attorney-in-fact full power and authority
to do and perform all and every act requisite, necessary or proper to be done in
the exercise of any of the rights and powers granted herein, as fully to all
intents and purposes as the undersigned might or could do if personally present,
with full power of substitution or revocation, hereby ratifying and confirming
all that the attorney-in-fact shall lawfully do or cause to be done by virtue of
this Power of Attorney and the rights and powers granted herein.  The
undersigned acknowledges that the attorney-in-fact, in serving in such capacity
at the request of the undersigned, are not assuming (nor is Magnolia Oil & Gas
Corporation assuming) any of the undersigned's responsibilities to comply with
Section 16 of the Exchange Act.

The undersigned agrees that the attorney-in-fact may rely entirely on
information furnished orally or in writing by or at the direction of the
undersigned to the attorney-in-fact.  The undersigned also agrees to indemnify
and hold harmless Magnolia Oil & Gas Corporation and the attorney-in-fact
against any losses, claims, damages or liabilities (or actions in these
respects) that arise out of or are based upon any untrue statements or omissions
of necessary facts in the information provided by or at the direction of the
undersigned, or upon the lack of timeliness in the delivery of information by or
at the direction of the undersigned, to the attorney-in fact for purposes of
executing, acknowledging, delivering or filing a Form ID, Form 3, Form 4, Form
5, Form 144, Schedule 13D or Schedule 13G (including amendments thereto) with
respect to the undersigned's holdings of and transactions in securities issued
by Magnolia Oil & Gas Corporation and agrees to reimburse Magnolia Oil & Gas
Corporation and the attorney-in-fact on demand for any legal or other expenses
reasonably incurred in connection with investigating or defending against any
such loss, claim, damage, liability or action.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Form ID, Form 3, Form 4, Form 5, Form
144, Schedule 13D and Schedule 13G (including amendments thereto) with respect
to the undersigned's holdings of and transactions in securities issued by
Magnolia Oil & Gas Corporation, unless earlier revoked by the undersigned in a
signed writing delivered to the attorney-in-fact.  This Power of Attorney does
not revoke any other power of attorney that the undersigned has previously
granted.

                            [Signature Page Follows]

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of the date written below.

Dated: October 29, 2018

                                        /s/ Steve Millican
                                        ------------------------------
                                        Steve Millican
                                        Senior Vice President - Operations