Zalbaag

I found this deck through the 'unloved' section of the site, so sorry for barging in if you didn't intend to shqre it with the whole site. I'll try to give some notes and hopefully they are helpful to you .

First of all, this looks like a control/copy deck that tries to play the opponent's stuff against them, which is pretty nice. I played a deck like that myself some time ago, and they are often difficult because you have to understand your opponent's deck as much as you have to understand your own. Some cool cards you might want to try are Nightveil specter; Ashiok, Nightmare Weaver; Control magic (which you already play) ; Domineering Will; Mimic Vat; etc.

I would play clones over changelings, since they directly copy a creature which ties in to your main strategy since they still work with Peer Pressure. Good cloners are Clone (duh); Evil Twin; Dimir Doppelganger, Clever Impersonator, Sakashima's student (expensive) and some others.

Something you definitely need to do is cut down on the number of different cards and colors in your deck. 5 colors is incredibly tough, you might want to cut down to 2 (3 if you have to), I think blue and black are your best colors. This will stabilize your manabase and give you more room for utilitylands such as thespians stage, mana confluence. Something that worked very well for me was Cromatic Lantern, which solves all your color issues if you get it on the field. some IMO, you need to cut all the tri-lands that enter tapped and replace them with basic lands. You also need to cut down on the one-of creatures ( you are right, the sliver overlord is cool but has no place here) and one-of spells.

Talking about spells, you have a number of super specific cards in here, such as the charms (are there any meaningful number of situations in which you have to kill clerics?) that you can cut and replace them with more catch -all answers like Doom Blade, Go for the Throat, Murder or Profane Command. Since you play clones and steal stuff, you will be behind your opponent in creatures most of the times. And since you can't always steal them with peer pressure you will need a way to kill them before they kill you. Hence a strong dose of kill spells.

Some other cards you you run are nice but you could run more or less of them. For example, Redirect is an awesome card ( I absolutely love it) that can stop counterspells, redirect killspells and so on, but it sucks if your opponent doesn't target anything. I recommend running only two unless your playgroup plays a lot of target cards. On the other hand you could definitely get away with playing 2 frost titans as a finisher.

Nice! I have a similar deck, but more geared towards humans. Depending on how 'cutthroat' your playgroup really is, you could also consider grave pact/dictate of erebos, grave betrayal,... If you need more one-drops, champion of the parish and bloodsoaked champion are great. Grim harusphex and Xathrid Necromancer are also great. And Cartel aristocrat is a great sac engine it you need it.