This Dhampir race is effectively a weaker version of a Drow, so I'll compare it to that.
- Ability Score Increase: The Dhampir gets to choose between the ability score bonuses of the Drow and those of the Dragonborn. This is perfectly in line with existing races.
Stuff the Dhampir gets:
Age & Alignment: Don't really matter from a balance perspective.
Size: The same as everyone else.
Speed: The same as almost everyone else, including the Drow.
Superior Darkvision: The same as the Drow.
Sunlight Sensitivity: The same as the Drow.
Dhampir Magic: The Dhampir gets a 1st level spell 1/day at 1st level, and a 2nd level spell 1/day at 3rd level. The Drow gets a cantrip, a 1st level spell 1/day at 3rd level, and a 2nd level spell 1/day at 5th level. This is the first real difference between the two. The Dhampir gets their racial spells 2 levels earlier, which is obviously stronger up until 5th level when it stops mattering. Not getting a free cantrip goes a fair way towards balancing this out, though.
Vampiric Heritage: I'll come back to this.
- Vampire Weaknesses: If you're incapacitated in a place of rest, you're probably asleep. It's pretty easy to kill someone who's asleep in general, so this doesn't really change much. There might be niche cases where it really comes into play but most of the time it shouldn't matter much.
Languages: Common and one other, just like every other race. The freedom to choose is nice, but hardly imbalancing.
Stuff the Dhampir doesn't get that the Drow does:
- Keen Senses: Free proficiency in the most important skill in the game. This is pretty strong.
Fey Ancestry: Advantage on saving throws against some of the most dangerous spells in the game, and immunity to the Sleep spell. This is also pretty strong.
Trance: Depending on your group and your DM, this might be important, but for most players, it's not going to matter a whole lot.
Drow Weapon Training: This is kind of nice, but most builds that need weapon proficiencies involve a class that gives them, so it's not that nice.
Overall, the Dhampir is probably a weaker version of the Drow. Their racial magic trait is a little better before level 5, but after that it's the same, minus a cantrip. Now for the elephant in the room.
Vampiric Heritage
Whenever you grapple, incapacitate, or restrain a creature, you gain the ability to bite that creature dealing 1d6 piercing damage. Furthermore, you can spend your turn drinking the blood of that creature, causing it to loss [sic] 1d6 necrotic damage. The creature's hit point maximum is reduced by an amount equal to the necrotic damage taken, and you regains [sic] hit points equal to that amount. The reduction lasts until the creature finishes a long rest, it dies if this effect reduces its hit point maximum to 0.
The problem with this is "the ability to bite that creature dealing 1d6 piercing damage". Does this require an action? A bonus action? No action at all? Does it give you the ability to do that when you grapple them, or anytime while you're grappling them? It doesn't really give us anyway to know.
The good news is that it doesn't really matter. Unless it requires no action and is anytime while you're grappling them, this is a pretty weak ability. If it's free when you grapple them, you can grapple, bite, let go, grapple, bite, let go and so on up to 4 times (if you're a Fighter). Except that you're just dealing 1d6 damage, so you'd have been better off attacking normally. Assuming your Strength score is 16 or higher, you'd have been better off punching them!
It only gets worse with other interpretations, too. If it requires an action and you can do it anytime while grappling, you're effectively using a turn to deal 1d6 damage, which is pretty much a joke.
Moving along to the other half of the ability, we have the ability to spend your turn drinking the blood of a creature. It's pretty clear what "spend your turn" means, and it makes for a pretty useless ability. Using your entire turn to deal 1d6 damage and gain 1d6 hit points might be ok at level 1 but it's going to become a joke pretty quickly.
The reducing maximum hit points part is useless because if you do enough damage to kill them with it, they would have died anyway. In general, D&D characters want to kill things, not inconvenience them. It could be used as a way to prevent an enemy regaining hit points, but there's a cantrip that does the job better and more efficiently.
So, overall, the Dhampir is pretty much a weakened version of the Drow race with some unique but useless features.
Having studied the book, you have some idea of what each Tarokka result can entail, and you can let this "foreknowledge" inform Madam Eva's reactions to the cards as they appear. If you draw
the 7 of Coins, you can hint that the location of the treasure isn't very far away; if you draw the 9 of Coins, Madam Eva might shake her head despondently and say "Maybe save this one for last."
It's easy to want to add merely emotional clues, to add color without giving too much away: "It is in a place of dread;" "I feel the presence of mournful spirits near this item;" "This place is cold and silent." But there's so little emotional contrast in Barovia that sentences like these can easily fade into the background noise of doom and gloom. Specific information will make your players' ears perk up, and if your goal is to create a memorable experience, you can afford to drop a few extra hints.
For example: Many of the speeches for cards that clue
locations in Castle Ravenloft don't actually refer to the castle ("We know it's in a crypt. Do we know where a crypt is?"), but Eva can add something about "beneath the Devil's tower" or glance nervously in its direction.
If the players feel like gabbing it up with Madam Eva about each card, trying to pry hints out of her, go ahead and respond according to the character you've built in your performance—but to add emotional texture to the scene, make her insist on total silence before she turns over the next card.
The use of a real deck is so effective because everyone loves props. The description of Madam Eva's tent provides a lot of inspiration for additional props: Mysterious lights, a crystal ball, and a black velvet cloth. I think this cloth is a good thing to focus on because you can slowly unroll it before you lay the cards down, which is a very evocative and almost ritualistic action. Even if your players forget what cards you drew, they will remember the appearance of that cloth unrolling across the table.
If you can't get a piece of black velvet, use whatever spooky-looking fabric you can get your hands on, and then change the words "black velvet" to whatever you're using when you read the description, so that the players will think you are following the details in the book exactly.
(On the subject of
Strahd's Enemy: Some of the results are more interesting than others. The book gives you the choice between NPC A and NPC B for some results, apparently according to what kind of Challenge Rating you want for the party's ally. Obviously you want to figure out your choices in this regard ahead of time. But for my purposes, I didn't really want my players to end up with either version of the Broken One, the Horseman, or the Innocent, so I just removed those cards from the deck. If you're not comfortable with the full range of randomness in the book, you can create "massaged randomness" without the players finding out.)
Best Answer
The relationship between the two adventures is fascinating and confusing. The short answer is: No, they are not very similar, at least not in a way that ruins or spoils one adventure for someone who's played the other.
On Castle Ravenloft itself:
Big Expedition to Castle Ravenloft Spoiler:
On the structure of the two adventures:
So your players who've played Curse of Strahd are sure to have a new adventure in Expedition to Castle Ravenloft. That being said, there are some inconsistencies and near-consistencies that you may want to watch out for.
Curse of Strahd contains a lot of Easter egg-like references to previously published Ravenloft adventures, and one could make a case that Curse "takes place after" I6, Expedition, and 4E's Fair Barovia. But it's not that simple. The name "Kavan" makes for a good example:
This kinda-sorta-continuity is characteristic of many people and places throughout Curse of Strahd's Barovia.
If your players are Legend of Zelda fans, this kind of thing is nothing new to them. If you're worried that they'll be confused, you can warn them that Expedition and Curse act like alternate universes to each other. In either case, I think that having already visited a version of Barovia won't diminish (and will tend to enhance) their experience of Expedition.