Section 54.18 - General duties and powers of guardian; limitations; immunity(1) A ward retains all his or her rights that are not assigned to the guardian or otherwise limited by statute. A guardian acting on behalf of a ward may exercise only those powers that the guardian is authorized to exercise by statute or court order. A guardian may be granted only those powers necessary to provide for the personal needs or property management of the ward in a manner that is appropriate to the ward and that constitutes the least restrictive form of intervention.(2) A guardian shall do all of the following: (a) Exercise the degree of care, diligence, and good faith when acting on behalf of a ward that an ordinarily prudent person exercises in his or her own affairs.(b) Advocate for the ward's best interests, including, if the ward is protectively placed under ch. 55 and if applicable, advocating for the ward's applicable rights under ss. 50.09 and 51.61.(c) Exhibit the utmost degree of trustworthiness, loyalty, and fidelity in relation to the ward.(d) Notify the court of any change of address of the guardian or ward.(3) No guardian may do any of the following: (a) Lend funds of the ward to himself or herself.(b) Lend funds of the ward to another individual or to an entity, unless the court first approves the terms, rate of interest, and any requirement for security.(c) Purchase property of the ward, except at fair market value, subject to ch. 786, and with the approval of the court.(4) A guardian of the person or of the estate is immune from civil liability for his or her acts or omissions in performing the duties of the guardianship if he or she performs the duties in good faith, in the best interests of the ward, and with the degree of diligence and prudence that an ordinarily prudent person exercises in his or her own affairs.2005 a. 387 ss. 100, 397, 401, 516.