Clerics, Druids, and Rangers use Wisdom for spellcasting, and Monks use Wisdom for their AC calculations and Ki save DC.

For Clerics, Druids, and Rangers, their spell attack bonus is equal to: Wisdom modifier + proficiency bonus.

Their spell save DC is equal to: 8 + Wisdom modifier + proficiency bonus.

For Monks, their unarmored AC is equal to 10 + Dexterity modifier + Wisdom modifier

And their Ki save DC is equal to: 8 + Wisdom modifier + proficiency bonus