Clutch of Earth

You can use your reserve of magic in combination with the power of the earth to slow creatures and empower your spells.  You gain the following benefits.

If you have a spell 2nd level or higher available to cast that meets one of the following criteria:   A) an earth based spell, B) a spell that allows you to shove a creatures OR C) a spell imposes the restrained condition, you can use a bonus action to reduce the speed of any landbound creature within 30 feet of you. The creature's normal land speed, as well as its burrow and climb speeds, decrease by 5 feet per level of the highest level spell that meets those conditions you have available to cast, to a minimum speed of 5 feet. This effect lasts for 1 round. Creatures that are swimming or flying cannot be effect by this affect. 

When using a spell that meet the criteria listed above creatures make their saving throws against the spell with Disadvantage.