Can you use the Feral Variant from SCAG on the variants in Mordenkainen?

What’s the in-house opinion about options from Sword Coast Adventure’s Guide that weren’t put in Xanathar’s?

A firbolg PC casts Booming Blade then uses hidden step to go invisible…

Is the attack made as part of Booming Blade magical?

Swashbuckler 3rd level casting Greenflame Blade – does it work with Fancy Footwork?

Are there any resources available for playing variant half-elf with traits from specific parent elf type?