Uthlar's Ambient Illusion

You create a harmless odor, physical sensation, or taste within a ten by ten foot square that you can see within range. 

If you create an odor, the odor must be of something that you have smelled before, and that scent is smelled by all creatures(as long as they have the ability to smell) within the cube. Trying to change the odor(via perfume or otherwise) will reveal the odor to be an illusion as the odor cannot be masked through such means.

If you create a taste, the flavor must be of something that you have tasted before, and the flavor is tasted by all creatures(as long as they have the ability to taste)within the cube. Trying to change the taste(with other flavors or otherwise) will reveal the taste to be an illusion as the taste cannot be masked through such means.

If you create a physical sensation(such as a faint wind, a tingling feeling, an electrical feeling, humidity, heat, etc.), the sensation must be of a kind that you have felt before, and the sensation is felt by all creatures(as long as they have the ability to feel that sensation) within the cube. Trying to change the sensation in any major way(such as trying to block a breeze or splash water over oneself to cool down) will reveal the sensation to be an illusion as it cannot be masked through such means. If a player chooses to change the temperature within the cube, they can only make the area feel 30 Fahrenheit hotter or colder respectively.

During the duration of this spell, the cube is static and cannot change position, and the illusion chosen cannot be changed once chosen. The illusion can/will be dismissed with an action or bonus action, when the duration is over, or when the spell is cast again.

If a creature uses its action to examine the sound or image, the creature can determine that it is an illusion with a successful Intelligence (Investigation) check against your spell save DC. If a creature discerns the illusion for what it is, the illusion becomes faint to the creature.