A save is DC15 and has extra effects if failed by 5 or more, does that mean at 9 or at 10?

If Calm Emotions supress a frightening effect…

I’ve been told Initiative is a skill, can rogues use it for Expertise?

I’ve been told Initiative is a skill, and thusly bards can use it for Jack of all Trades. Can rogues use it for Expertise??

Does a creature riding the displacer beast benefits from its Avoidance and Displacement traits?

Oni can Change Shape into Large giant OR back into true form—but…

Does compelled duels target suffer any effects if they make their initial saving throw?

Does Leomund’s Tiny Hut have a floor?