We have a PC that is getting very sneaky with his Sacred Flame application. Its fun outside-the-box play but if he carries a hand mirror or uses scrying spells its going to become far easier.
Can a mirror allow use of Sacred Flame around a corner?
Can a PC scry to the other side of a door and use this sight to activate sacred flame?
Rules for Total cover:
A target with total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. (PHB 196)
Sacred Flame Text:
Flame-like radiance descends on a creature that you can see within range. The target must succeed on a Dexterity saving throw or take 1d8 radiant damage. The target gains no benefit from cover for this saving throw. (PHB 272)
Sacred flame specifically states "that you can see".
It is also confusing what the "area of effect" might be.