Forgive me if I am mistaken, but I think there is an error in the code that makes it so that Trick:Soothe works ONLY against bosses, rather than against everything that is NOT a boss.
You check ent.isNonBoss(), rather than !ent.isNonBoss() like you do in Trick:Riot.

I've tried this ingame and I get the error message for "attempting to cast the spell on an immune or boss target" when targeting regular mobs, but not when targeting a wither.

PS: Love the icons for those two Tricks!