To see my overview of the first 13 episodes of season 2, click on this magical link. And I'll repost my rating system again for the episodes. It's imprecise, but I like it:
★✯✯✯✯ - pretty bad
★★✯✯✯ - not so good
★★★✯✯ - pretty average
★★★★✯ - good
★★★★★ - pretty great
'The Silent King'
Finn takes down the cruel king of the goblins, and winds up having to take over in his place, but this new position limits him from being allowed to do pretty much anything at all. Very predictable and relatively uninteresting. Nothing happens here worth noting.
'The Real You'
Finn gets magic glasses to try to impress Princess Bubblegum during a science meet, but he winds up a little too smart and this leads to danger. I feel like I've been saying this a lot, but this is another episode that's relatively uninteresting. Super smart Finn does have a few pretty funny moments, though.
'Guardians Of Sunshine'
Finn and Jake think they'll have better luck playing BMO's game if they were physically inside of it, so you can guess what happens next. This is one of the earliest visually experimental episodes in the show, and that's something I always find praise-worthy. It's filled with good moments and I really like its style. A definite season 2 highlight.
'Death In Bloom'
Finn and Jake are given the duty of protecting Princess Bubblegum's plant, but when it dies they have to go to the Underworld to bring it back. One of Peppermint Butler's best episodes (he has a personal friendship with Death...the weirdo) and filled with cool visuals.
Finn longs for some human connection, and finds a race of people underground who appear to be human. He tries to teach them about life above the surface. The first appearance of Susan, has potential as an emotional episode, but did nothing for me. Not bad, not good.
Jake prepares a surprise for Finn's birthday, but they have to take a train to get there. On the way, people start to die on the train and they must solve the mystery. Obviously you know things aren't as dark as they seem but that doesn't keep the mystery itself from being a fun one to watch unravel. This show is always good at stuff like that.
'Go With Me'
Finn tries to find a date for movie night. He tries to get Marceline's help to convince Princess Bubblegum to go with him. Not one of the better teen romance episodes around, but this show hadn't quite figured out how to make the angst work in its favor at this point.
'Belly Of The Beast'
Finn and Jake try to figure out what's going on to make a giant sick. Turns out there are a bunch of firework-shooting party teddy bears inside of him. Yeahhh, this is a bit of a weird one. The gooey stomach animation is pretty gross, the concept is...unique, but it's not particularly entertaining.
Finn and Jake go through a maze that's meant to grant a wish to anyone who completes it. Jake stretches himself throughout. If you've ever wondered if Jake has a limit to how far he can stretch, he indeed does. This is one of the better dungeon crawl episodes, and pretty funny, too.
Finn and Jake set out to make a movie to screen for their movie night. But they have differences in what kind of movie they want to make. I have a soft spot for movies and episodes about the making of films, but this one just doesn't have enough to it to make it particularly stand out. But I still enjoyed it.
Princess Bubblegum tasks Finn and Jake with the duty of stopping The Lich from regaining his powers. But the Ice King gets in the way and causes some very big problems. The Lich is an incredibly dark and creepy villain, and with his introduction here, we have easily the best episode of the second season. This is one of the most thrilling episodes of the first few seasons, and leads into a really good follow-up.
Due to Ice King's stupidity, Princess Bubblegum winds up possessed by The Lich, but no one knows this right away. But she starts acting really weird. Originally planned to be the season finale, the second part of this two-parter isn't quite as good as the first one, but it still a pretty great episode. It's suitably dark, and the ending allowed for some interesting material for the beginning of season 3.
But instead of the proper finale, this is the one they ended the season on. Marceline pranks Finn and Jake into thinking they're vampires. There are ghosts involved, too. Apart from Marceline's first episode 'Evicted!' (which I still think sucks), this is probably the worst appearance she had in the first two seasons. I didn't find any of this funny, and it felt much, much longer than 11 minutes. Very skippable.