Here's what you missed:
1. Lola taking a bath. This, as it turned out, was a major plot point. Not making this up.
2. A return to the entire Lola taking a bath plot, as an even MORE major plot point this time, complete with SCANDAL and CHARACTER DECEPTIONS and TERRIBLE COSTUMES.
3. Fraternal twin ghosts who initially seemed OUT FOR BLOOD and later turned out to be OUT FOR A SNOWBALL FIGHT.
4. Characters rather understandably deciding that rather than pay attention to, say, the deadly fights between Catholics and Protestants and various extras constantly dying around them, they should go off and read a sex journal and frolic in a fountain. And then going and doing just this.
5. Catherine d'Medici getting her feet poked at by birds, and later forced to spend an entire scene inside a metal tank sealed around her neck like yes, I am also not making this up.
6. Also, Catherine d'Medici getting oral sex from a ghost. No. Really.
7. The arrival of King Antoine of Navarre (someone the show seemed to occasionally confuse with his son, Henri of Navarre, later Henri IV of France, because this is not really the sort of show that cares about those sorts of differences) who initially, alas, didn't seem to stand out much among all of the other characters, so the show had him throw an orgy and then threaten people which meant that he still didn't stand out that much among all of the other characters.
8. Francis going ahead and becoming king and then being just terrible at kinging.
9. Mary, Queen of Scots becoming a passionate defender of religious tolerance and Protestants.
I know, I know.
10. A character getting sacrificed to cure another character's ear infection, and by "sacrificed," I mean "gently killed with poison and given a nice sad death scene while another person happily noted that this was saving the sacrificed person a lot of grief," like, THIS SHOW.
11. Another character covering her chest with blood and then having sex with a random servant during a siege like you know, everyone has their own ways to celebrate what might be their last moments on the planet, or, in this case, possibly the show.
(This was apparently supposed to be some blood ritual meant to remind us that a) pagans, the people who live in the woods and chant a lot about blood, were on this show back in the first season, and b) give two characters some sort of soul bond which will allow them to feel each other's pain or whatever. I would be kinda interested in where this is going except that I'm pretty sure that, like the ghosts, it's going to end up going to either sex or snowball fights.)
12. The show's first gay couple, who turned out to be easily blackmailed priests. So that was nice.
13. Yet another love triangle for Mary Queen of Scots only less interesting for the most part since new Love Triangle Guy (called by the show Louis, Prince of Conde, something that I'm sure the ghost of the real Louis, Prince of Conde, has his ghost lawyers on top of right now since if ever a television show could be accused of libeling a French aristocrat, this show would be it) was very boring until a knife got brought out and even then.
(Love triangles, done right, can be awesome – as a recent episode of Agents of S.H.I.E.L.D. demonstrated, and Reign has managed decent love triangles before. This wasn't one of them, mostly because Mary had a number of other less boring love triangle options available.)
14. A rather unexpected touch of historical accuracy as Mary Queen of Scots kept making terrible decision after terrible decision after terrible decision. Actually this one makes the historical one look rather sensible, restrained, and in complete control of her emotions. Especially because with the historical one, I can at least explain it by "She thought Bothwell was one hot, sexy dude," which if not exactly borne out by the pictures we have of Bothwell, at least offers an explanation, whereas with the TV Mary I usually have no idea why she is doing anything that she's doing.
15. Catherine d'Medici strangling someone and banging said someone on the floor and NOBODY ELSE NOTICING THIS AT ALL. It's good to be queen.
16. A great moment when a brothel madam looked down at the attractive man kneeling before her, earnestly offering honorable marriage, and said, nah, I'm good. Thanks.
17. An amazing insistence by the show that prostitution is a solid road to wealth, success, and excellent champagne. Also, poisoning opportunities.
18. In a related scene, Kenna, celebrating that the three ladies in waiting are all now fallen women in one way or another which means they need to drink up. You go, Kenna, you go!
19. Toby Regbo, who plays Francis, learning to act, if not quite convince us that he is a king until the finale when he went into a SHRIEKING FORCE OF RAGE on a chained up prisoner in a dungeon along with a few other moments which if not exactly strictly kingly did convince me that Francis knows his way around a dungeon, if you know what I mean, and I think you do.
A few of the other actors also leveled up, meaning that this is no longer a show where Megan Follows (Catherine d'Medici) acts, and everyone else is just sorta there. I am as surprised as you are. But for those tuning in for the bad acting: fear not. Leith is still on the show.
20. And, as I hoped, Elizabeth I of England showed up, looking nicely demented, quite possibly because despite a nice attempt to put a collar thing on her, her gown was not exactly like any of the gowns the historical Elizabeth wears in her various portraits, and when I say "not exactly like" I mean "not at all alike." This bodes well for the third season, although not that well – Elizabeth I seems to be interested in the boring Conde guy. Aim higher, Elizabeth! Much higher! Or at least more interesting.
One warning: For some unclear reason, Reign decided to throw a rape plot into all of this, and although I thought the rape itself was handled as well as rapes on television are ever handled (that is, not well), and wasn't, in my opinion, overly graphic, I thought the aftermath was handled rather less well, so if not very well handled rape storylines aren't your thing, I would recommend skipping the middle of the season, or the show altogether.