You choose a spell of 5th level or lower that you can cast, has a casting time of 1 action or less, and is able to target you. While casting Contingency, you also cast that chosen spell and spend mana for both, but the chosen spell does not activate immediately. Instead, you set a specific trigger for when it will take effect, such as Water Breathing activating when you are submerged.

When the trigger happens for the first time, the chosen spell immediately affects you, whether you want it to or not, and Contingency ends. The spell can only affect you, even if it normally targets other creatures. You can only have one Contingency active at a time, and casting it again ends the previous one. The effect also ends if the required material component is no longer on your person.