In a common form of oil and gas lease, there is a warranty provision that typically begins, "Lessor herein agrees to warrant and forever defend..." The poor landman or attorney will add an interlineation to read, "Lessor herein does not agrees to warrant and forever defend..."
This is sloppy work in my opinion.
I am not an attorney and I am not giving legal advice. My business advice is to take this clause to your legal advisor to determine if it is satisfactory to include in your lease:
"Lessor makes no warranty of any kind, express or implied, as to title to its interest in said land or its oil and/or gas interests thereunder, and there shall be no liability on the part of Lessor to refund any amount received under the Terms of this Lease (including but not limited to bonuses, delay rentals and/or royalties) in the event of any title failure, nor shall Lessor be required to furnish any bond, abstract or indemnification to any person or entity regarding its title to said lands, such matters of title to be determined at the sole cost, expense and risk of Lessee and not of Lessor."
This is the language that I put in my leases instead of deletion of warranty.