A couple of the cards from this side of the release got reviewed alongside the main set. Some dimir pirate and one other that I noticed.
Sivitri, Dragon Master 0
Too few blue and black cube worthy dragons and even if it were the -3 ability is not exactly exciting. It is close to, often worse than "draw a card" which for a three loyalty cost is a big no no. The +1 is interesting but sadly gives too much choice to the opponent and doesn't gel well with how planeswalkers play. So for your four mana you get to not affect the board in any way and then probably die due to having such a rubbish card.
Jared Carthalion 2
Well, if he lives a couple of turns you can have a pair of 8/8 Kavu. Congrats. For a card so colour intense I want more immediate impact than this offers. I want game swinging plays, not a pocking 3/3 kavu. Trample is nice and goes a long way but most mono green planeswalkers do a better job of impacting the board.
Dihada, Binder of Wills 3
The +2 is not only narrow but a little but poo as well. It can allow you to race and pressure effectively if you have an appropriate legend in play. Good luck with that. The -3 however is very tasty, potential card draw but also potential mill and huge mana influx. Three cards in the bin, one in hand, and three treasure is amazing. Dihada can literally be a 0 mana mill 4 that leaves a somewhat relevant planeswalker in play! Feels like you can play this in a legend (historic) deck and a self mill deck. Not many self mill decks are white and not many decks at all are legend focused but cards like this go a long way to helping reverse those trends. Interesting if nothing else.
The Mana Rig 3
This can just be an Arcane Encyclopedia. Indeed you can pay 6 and draw 2 each turn if you want making it strictly better. You can even pay 21 mana and have this mimic the effect of a Dig Through Time! It is then better than Arcane Encyclopedia for a second time thanks to producing powerstone tokens. Sure, powerstone tokens don't help much with casting gold cards but they do help a lot with activated abilities, such as those found on the Mana Rig. So, you don't need artifacts to play with this nor do you entirely need gold cards to trigger it. Certainly the more you have of the latter the more interesting this becomes. It is a bit slow and narrow for most cubes but it is somewhat close to the mark and certainly something I would look at in a variety of more build around decks.
Greensleeves, Maro-Sorcerer 3
This is competing with the likes of Wisperwood Elemental and Biogenic Ooze and I like this least of those offerings. To get instant value with this you have to play it off curve and have lands, and ideally a supply of them for the next few turns at least. Certainly this has seemingly some good upper scaling on the others but we want to look at floors first when evaluating and there Greensleeves is less good. Powerful and playable certainly but too many better alternatives to have much impact.
Torsten, Founder of Benalia 6
This does what?! All of them? Then that as well?! OK. So, for seven mana we are going to draw about five cards as well as making a 7/7 that in turn dies into an army of 1/1s. This is a very very serious card but it does cost seven. And it is gold. And it costs seven. I see this more as an impressive source of value than a threat. You are playing it for the huge refill on gas at no tempo cost. The threat of Torsten is in this huge influx of gas rather than the body. The 7/7 has no evasion or other abilities making it rather hard to get good results out of. It will get chumped a lot and do very little actual damage. It is super awkward to answer however, it is more effective Wrath protection than it is a threat. People will not be able to risk facing off seven 1/1s if they are foolish enough to kill Torsten and so they will have to bounce or exile him before they can Wrath. Generally having Torsten in play will make things awkward and annoying for the opponent and most of that is due to the on death trigger. There is a decided wiff of the Griselbrand about this card. Obviously less universally playable and less threatening and less powerful, but still, that sort of card in that sort of ballpark which is potent and merits testing.
Shanid, Sleeper's Scourge 2
Perhaps a bit 4 mana to be a great value card but it is too cool for me not to play this in a legends deck if I do one any time soon. It just means that deck will be a pretty low tier one!
Jedit Ojanen, Mercenary 2
Mediocre power level and not great colours for a legendary subtheme synergy card. Perhaps good with the mercenary tribe from Masques block in some way?
The Lady Otaria 3
Finally some proper payoff for dwarves. A little awkward on colours with most dwarves being white or red but none the less too powerful to overlook for the tribe. Dwarves happen to have a "Recruiter" as well meaning this Lady can setup to hit for 4 with ease. So, the ceiling on this is making a 5/5 on turn two (on the back of three one mana dwarves) and then instantly hitting four more dwarves there after every turn! Spicy. This makes me want to go and build some dwarf decks. Sadly not much place for this elsewhere.
Historian's Boon 2
Build around only card but pretty fun. You need high saga count and high enchantment count and are likely better off with Sigil of the Empty Throne but this is cheaper and does do something itself right away. Perhaps there is a build where you want both.
Emperor Mihail II 3
A solid enough top end merfolk that helps plug a few of the holes in the tribe. The power level here is fine but the suitability is such that I will certainly be playing this in singleton fish decks. Typically they lack good sources of value and token production both of which this does pretty well. What this doesn't do quite so well is being low cost or all that impressive of a body. You also have limited slots at the top end, you mostly want cheaper merfolk and so the bar is rather raised for those few costlier fish you can run.
Rosnakht, Heir of Rohgahh 6
This might be legit good both as a build around in a couple of directions and even as a card you might just play in some decks. First build around style of deck is the 8-whack aggro combo lists and the second is a Feather the Redeemed heroic style list. This guy does a lot of good work in both of those. As for just putting this in a deck, it would need to have some things I would want to target Rosnakht with as well as an aggressive lean and a heavy count of cheap dorks. A one drop dork with battlecry is good but with no power itself it can be somewhat of a dud draw. I might even play this in a list with nothing that can trigger the heroic if I had a lot of cards that improve with pump such as Dreadhorde Arcanist. Verdict on this is that it can be very powerful and has a lot of potential homes but that it is insufficiently able to stand up alone to be a card you want in cube drafts.