D&D 5E Reduce max hitpoints while in wildshape?

[Wolfwood2]

If a druid is in wildshape and hit by an attack that reduced their maximum hitpoints, such as an attack from a wight, does that reduce the maximum hitpoints of both base and wildshape forms or does it only apply to the hitpoints of the animal/elemental form?

If a wight reduces the max hitpoints of a druid's animal form to zero, but the druid's base form would still have hitpoints even if the max hitpoint reduction effect were applied, does the druid die instantly or simply revert back to base form as standard when a wildshape's hitpoints are reduced to zero?

Conversely, what if a druid is in a form that has more hitpoints than their base form (such as earth elemental form) and has max hitpoints reduced to the point that their base form would have zero hitpoints, but the wildshape form still has hitpoints to spare?

Does any of this change for polymorph instead of wildshape?

If the max hitpoints reduction does apply to both forms, does this mean that hitpoint-draining undead are uniquely dangerous to Moon Druids, who usually trade low AC in their animal forms for not having to worry about damage carrying over?

I'm going to be playing a Moon Druid in a new campaign, and the DM has mentioned that he's considering running Curse of Strahd. I figure I'd better get a grip on this stuff before we run into wights and spectres and such.

I wrote in to Sage Advice, but who knows if they'll tackle the question. Looking to find out what the forum thinks and how you've ruled in your games.

 

[The Crimson Binome]

I'm pretty sure that it only affects your new form. If you turn into an animal with 23 Hit Points, and your maximum is drained by 20, then you're an animal with a maximum of 3 Hit Points and when you go back to a druid you're fine.

If you turn into an animal, but you would take over-kill from a draining attack, then the remainder drains from your druid shape. If you were an animal with 3 Hit Points left, and you get hit by a draining attack for 10, then your animal form dies and your druid form takes 7 points of drain.

This is the flip-side to how most animals are susceptible to Power Words, even if the underlying druid would be immune. Your animal form is its own thing, with its own stats, for better or for worse.