[RPG] Can a druid Wild Shape into Sangzor from the Curse of Strahd adventure

Yes, if you are a level 8+ druid (or level 2+ Moon Druid)

The rules on wildshape state:

[...]you can use your action to magically assume the shape of a beast that you have seen before.

There is also the table of CR limitations:

\begin{array}{r|lll} \text{Level} & \text{Max CR} & \text{Limitations} & \text{Example} \\ \hline 2nd & ¼ & \text{No Flying or Swimming} & Wolf \\ 4th & ½ & No Flying & Crocodile \\ \text{*8th} & 1 & & \text{Giant Eagle} \end{array}

This table shows that you must be a level 8+ druid to change into a monster of CR1.

*Unless you are a Moon Druid, which can choose a CR 1 creature as early as level 2:

Starting at 2nd level, you can use your Wild Shape to transform into a beast with a challenge rating as high as 1

In the Curse of Strahd Campaign book, Sangzor is described as follows:

Sangzor is a giant goat known for its supernatural resilience and evil disposition. [...] Modify its statistics as follows:

• It has an Intelligence of 6 (-2 modifier) and is chaotic evil.

• It has 33 hit points.

• It has resistance to bludgeoning, piercing, and slashing damage from nonmagical attacks.

• Its challenge rating is 1

So the campaign says Sangzor is a Giant Goat (MM p. 326) with the modified stats above. A giant Goat is a CR½ beast which means you're good on the CR and creature type as well.

Therefore, if you have encountered Sangzor, you have (presumably*) seen him and if your druid is at least level 8 (or is level 2+ and Circle of the Moon), it clears the CR limitation.

_{The campaign, as written, states "The mist and snowfall prevent seeing anything more than 60 feet away." So if your party was a little spread out and the goat was defeated while the druid was more than 60' away from the action, it is possible for the party to defeat Sangzor without the druid seeing it to add to its repertoire of forms}