As an action, you can create a vial of red liquid that continuously contracts to a tiny bead and then expands to color the clear liquid around it. A creature can drink the contents as an action to grow larger or smaller for the duration.
Everything the creature is wearing and carrying changes size with it. Any item dropped by an affected creature returns to normal size at once.
Enlarge. The creature’s size doubles in all dimensions, and its weight is multiplied by eight. This growth increases its size by one category—from Medium to Large, for example. If there isn’t enough room for the creature to double its size, the creature or object attains the maximum possible size in the space available. Until the effect ends, the creature also has advantage on Strength checks. The creature’s weapons also grow to match its new size. While these weapons are enlarged, the creature’s attacks with them deal 1d6 extra damage.
Reduce. The creature’s size is halved in all dimensions, and its weight is reduced to one-eighth of normal. This reduction decreases its size by one category—from Medium to Small, for example. Until the effect ends, the creature also has disadvantage on Strength checks. The creature’s weapons also shrink to match its new size. While these weapons are reduced, the creature’s attacks with them deal 1d6 less damage (this can’t reduce the damage below 1).
You can expend 1 additional catalyst to enlarge or reduce the creature’s size one additional step.
Enlarge. The creature gains 10 temporary health and its reach increases by 1.5 meters.
Reduce. The creature had advantage on Stealth checks and can move through tight areas.