Moonbeam

When does the Moonbeam spell damage trigger?

RAW: "When a creature enters the spell’s area for the first time on a turn or starts its turn there, it is engulfed in ghostly flames that cause searing pain, and it must make a Constitution saving throw. It takes 2d10 radiant damage on a failed save, or half as much damage on a successful one."
Ruling: If the damage occurred when the caster moved the Moonbeam spell over a creature, that would be pretty busted - a 60' sweep of damage each turn is bonkers. We have interpreted this to mean that the damage happens either:

• The first time in a turn a creature is moved into the beam (of its own volition or otherwise), or
• When a creature starts its turn in the Moonbeam's area of effect.

There's a discussion about this that supports this ruling, but the links to the Sage Advice mentioned for it are broken.