Soothing was released as Kindness's 2nd Epic Effect card added in Beta 11.0 during the UnderCards 1 year Anniversary. However, Beta 17.0 changed it to a Rare. Previous Versions can be found here.
When used, it will set the stats of a monster of your choice to 3/2.
Combo's (allies)[]
Using this makes a monster able to avoid cards like Muffet's Pet as well as Asgore, but makes it fairly weak. However, you can combine it with Force of Nature or Feast in order to bring their HP back up. When using the spell on allies, it's best used on low stat cards Sans to give him more attack and more survivability.
Combo's (enemies)[]
You can also use this on enemy monsters. By bringing it to 2 HP, you can instantly kill it with the help of Temmie, Vulkin or Spider. Or it can be used to weaken powerful monsters, such as a Mettaton NEO, as it will bring down its attack and also make it more difficult for the enemy to trigger its dust effect. Keep in mind that using it on The Heroine will still make her return with normal stats when revived.