This card is incredible. Games are either a race or a big grind in this format, and it’s fantastic in both scenarios. Dimir decks should be able to recur it at will, and Golgari decks should be able to recur it enough. It’s also worth noting that because of the way the rules work, if you surveil the Blood Operative to the graveyard you can immediately pay 3 life.
Second Pick: Conclave Tribunal
Conclave Tribunal is stronger in Constructed than in Limited, but it’s still pretty good in Limited. You’re happy paying full retail for the effect, and sometimes you double-spell because of the convoke.
The same principle applies here. I’d rather take a 1-colored card if I can, especially if that color is red. Direct Current is better in Izzet than it is in Boros, where having spells matters and you finish more games off with the direct damage, but it’s going to be good in any red deck, and most Boros decks cap at 5 mana so it’s an anti-flooding measure too.
Second Pick: Gird for Battle
I love Gird for Battle. It’s almost a Boros card, since there are Selesnya decks that aren’t interested in running it, but I think it’s extremely good in the good Boros decks. A lot of the time you’re feeling “safe” with your blocks and then your opponent spends 1 mana, plays a Gird for Battle, and suddenly you can’t block anything for the rest of the game. I believe that this is a better pick than Hypothesizzle.
Murmuring Mystic is unassuming, but it has a way of running away with the game. It’s better in Izzet since you want many spells anyway and a lot of them have jump-start, but it’s also going to be good in most Dimir builds. As a 1/5, it also survives a lot of the removal spells in the format (Direct Current, Hypothesizzle, Dead Weight, Artful Takedown, and even Luminous Bonds doesn’t do much against it).
Second Pick: Dead Weight.
Find // Finality is going to be amazing in any Golgari deck, and it’s an easy splash in Dimir or Selesnya because you can just cast the first half if you have to. If you’re playing a grindy, attrition-based game, you can get your two best creatures back, and if the board is stalled, then you have something pretty close to a Duneblast.
Second Pick: Goblin Cratermaker
This format is full of 2-drops, and Goblin Cratermaker is one of the best. The dedicated Boros 2-drops are better in Boros, but this is a flexible card that you can sometimes even splash for. I think it’s better than Artful Takedown, since that goes in only one deck to begin with (though Artful Takedown can also be splashed).
I like most split cards in this set because they’re very flexible—you can splash them in basically anything, even if you have only one source. The Integrity side of Integrity // Intervention is already good enough to see play in Izzet, and if I have as much as one red source I’m slamming it in Selesnya as well (and some Selesnya decks might want the pump effect). If you’re Boros, then the card plays triple-duty of removal, pump, and finisher, all of which are effects you’re looking for.
Second Pick: Kraul Harpooner
Kraul Harpooner is a weirdly-worded card, but once you understand what exactly it does, you’ll realize that it’s pretty good. There’s no better feeling than sniping a Healer Hawk or Nightveil Sprite in the early game, and it trades with any big flyer in the late game. This is a card any green deck is happy to have.
It might be weird not to pick Hatchery Spider, but I don’t think that it’s a very good card. 7 mana is a lot, and the ability is a lot worse than it looks. I’ve missed with it plenty of times when I had X equal to 3 or 4. Sometimes you hit and it’s great, but it’s rarely better than a 7-mana card should be. I’d play this in most Golgari decks, but I’d be very disappointed to first pick it, and I think all the good commons are stronger.