In Nevada, the defense of unilateral mistake is available where:

1. Mistake made by one party at the time of formation of a contract concerning a vital fact upon which they based their bargain;
2. The mistake materially and adversely alters the contract;
3. That party does not bear the risk of mistake; and
4. The other party has reason to know of the mistake or caused it.

Unilateral Mistake may allow a party to a contract to obtain relief from that agreement.  Home Savers, Inc. v. United Sec. Co., 103 Nev. 357, 358-59, 741 P.2d 1355, 1356-57 (1987) (adopting Restatement (Second) of Contracts § 153 (1981)).  It occurs when one party makes a mistake as to a basic assumption of the contract, that party does not bear the risk of mistake, and the other party has reason to know of the mistake or caused it.  Id.