Can I command my Find Steed mount attack seperately while not mounted?

If a player is a Knowledge cleric double proficiency bonus in History…

Which save DC is used when multiclassing?

Can a sentient magic item attune to other magic items?

I think Thunderwave is the red area. My friend argued it is the yellow. Who is correct?

I believe the caster can also be 5′ right or left – not required to be center of the face they are touching