After spending about 50 hours in this game, I have a good feeling that Shadowheart needs to be slightly reworked as she feels a bit lackluster compared to the other companions, and here is why.
I currently believe that The 3 best classes in the game are Ranger, Rogue, and Warlock because of how oppressive they can be from a range and without spending resources that must be regained upon long resting. Ranger gets Hunter's Mark Damage off of both landed weapon attacks and Colossus Slayer procs (this may be a bug or a misremembrance, but I believe I found this in the combat log when I looked back one time), which if you keep the ranger well out of reach, they do not have to risk losing this mark and can just blast away. Thief Rogues can sneak before and after sneak attacking from a range as well as get a ton of off hand attacks due to multiple bonus actions should they need to run out of cover. Warlock Eldritch Blast is strong and reliable and doesn't require advantage or concentration unlike the other two listed before.
Now this may seem like a tangent but the bottom line is that ranged dps at a low cost is the most effective tactic by far in this game, and its because melee classes that do not specialize in DEX just straight up don't get enough AC to survive the thick of the fight against the swarms of enemies you have to face in this game. The only heavy armor in early access is Ring Mail at a measly 14 AC and this is problematic because it means DEX is as important as Con for melee survivability. Shadowheart is lacking in both of these with 9 DEX (giving her -1 to her AC unless she uses Ring Mail which she isn't proficient in) and 13 Con (only a +1 to hp per level).
Now Shadowheart is forced to be trickery domain which I believe hasn't really held up in my opinion to either flavor or game design due to the problems I have listed above. CD: Invoke Duplicity only gives advantage if the assailant is within 3 meters of the victim, is completely stationary, and requires concentration to maintain, which takes away from her other useful buffs or debuffs that she can use during combat. Her Concentration is another problem in itself, as it just doesn't last due to having only a +1 to her con saves anyways, and not enough AC to avoid damage. Clerics are usually filling the role as tanky front line fighters, but Shadowheart often dies very quickly in the thick of most fights because she doesn't have much AC even with a shield, can't keep up her support spells well, and doesn't have much HP to stay alive with d8 hit die and +1 to CON. You can keep her as a backline healer, but when she isn't healing, she's throwing measly cantrips which have way lower hit rates than other classes offensive spells
While this is a highly critical post, it isn't to say that Shadowheart isn't an important character to have. Inflict Wounds and Guiding Bold are both insanely strong spells that have huge impact even in group fights. Considering that those first three classes are so powerful, however, Shadowheart is much more efficiently used by providing bless and using heals in the backline, a role that is shameful compared to what Clerics are supposed to represent in traditional DND.
I would recommend allowing players to choose Shadowheart's domain as soon as we get her. I would almost go further and say you should let us point buy the stats for each origin character we add to our party as to allow more experienced dnd players like myself more room to customize our parties as more challenges are added to the early access. You could argue that Shar is most fitting to go to Trickery Domain and that is why she has to be this way, but then why can you have Shar as your Deity when you make a custom Cleric either Light or Life Domain?
I understand that this is still within the first week of early access and your studio is working quite hard in order to provide more content, which I assume includes heavy armor. Thank you all for your consideration and please continue working hard to make this game better. Apologies if my thoughts seem redundant or disorganized as I have been spending the last 5 days grinding this masterpiece in the making non stop.
