I'd take out Convolute, Condemn, Negate, and Cancel for Path to Exile, Dissipate, Hinder, and Puppeteer.

+1

if you have a way to make the stolen creature indestructible then you can keep the creature and keep stealing more.

Avacyn, Angel of Hope

cards that come to mind are Darksteel Plate , Deathless Angel , and Spearbreaker Behemoth for the big creatures and if you can get to her ultimate Elspeth, Knight-Errant . the obvious one is Avacyn, Angel of Hope .

I am thinking maybe I will put in a darksteel plate instead of one of my equipments already there, and a deathless angel in place of one of my big guys if I can acquire one. Unfortunately, Avacyn and Elspeth are out of my price range, while the behemoth is the wrong color.

dur, my bad

Huh, this is the only other Merieke Ri Berit Commander/EDH deck I've seen. I'm glad someone else recognizes her potential. She's can be the ultimate trump card if given the chance.

The previous comments are correct, indestructibility is a good way to keep stealing creatures, if a mana-heavy one. However, she has a trick up her sleeve in the form of mass control. By making good use of checks and priority, you can manipulate the stack in a way that lets you take control of as many creatures as you desire at the same time. You'll need to load up your deck with more than a few "untap target creature" abilities, but the payoff is worth it. A comment I left on my deck explains how to do it.

I'd also consider finding more ways to protect her. She seems innocent when playing with people you don't play often, but once someone figures out why she's so potent, she'll be an immediate target, and boy is she fragile. I'd recommend using all the shroud/hexproof equipment and auras you can get your hands on, even if they'd be sub-par by the Casual format's standards. Blue has tons of them. Also, this deck shouldn't be without card:Champion's Helm for any reason.

Check out my spin on it: The Siren's Army. Keep in mind that I haven't worked on it in awhile, and I don't have access to nearly the card pool you seem to, but you might find some ideas of your own. Use her wisely, she's more powerful than most people realize.

@kayo: yeah, I agree with how good merieke can be if unopposed, but in my meta, removal is plentiful, both targetted and global, so expecting her to last for more than a few turns is unrealistic. I tend to use her as a repeatable removal spell with some hope of keeping the creature for longer. The deck has evolved from basically what you have into a very control-focused build, with the intent of neutralizing the opponents via removal, counterspells and good old fashioned politics (my favorite), then using two or three good things for the win. It's surprising what this deck can bounce back from.

I took your advice and added champion's helm as well as swiftdeath's suggestion of darksteel plate, so maybe she will survive a bit longer for me to get a good lock.

HATE. That is all.

A good finisher is Dovescape + Elesh Norn, Grand Cenobite . or something like it. Your best bet is infinite combos for an instant win. since you have access to black here are a few of my favorites: Triskelion + Mikaeus, the Unhallowed and Sanguine Bond + Exquisite Blood .

Also, Thopter Assembly Time Sieve is good as well.

I got a Merieke-Deck too... ...love her.

card:Minamo, School at Water's Edge is the BEST card for Merieke.

Weathered Wayfarer is a good land tutor, maybe with Mother of Runes , Serra Ascendant , Hex Parasite and Ranger of Eos as a toolbox tutor...

If you play multiplayer, I would cut some counterspells... ...they are only good in 1on1s.

Mortify is nice.

There is some nice synergy with Merieke, if you can make creatures indestructible (e. g. Eldrazi Monument , Deathless Angel , That Which Was Taken , Avacyn, Angel of Hope ...), because Merieke would "destroy" the creature you got control of.... ...so you will keep them permanenty and they are indestructible, even if Merieke dies or gets unttapped).

Unbender Tine ist nice for Merieke too... ...and works as mana ramp sometimes.

If finishing off is the problem why not try a planeswalker like Sorin Markov ? Leaving an opponent in 10 life should do the trick specialy on life gaining decks or you can snipe off and then control the player for a turn (great flavour)

If not look for some painfull black spells, there are many that can hurt a LOT. You can check some in this deck I once tried to use them lol Shadow+Evil spells

i've got a merieke deck too and i love it to pieces. it's up on the site if you want to take a look.

might i suggest some other things that'll allow her to untap? card:Minamo, School at Water's Edge and Unbender Tine are great suggestions. i usually end up tutoring in a Freed from the Real if i can. Intruder Alarm is pretty fun with her too. going along with what Ghoul was saying; i put in Aegis Angel and Darksteel Plate which can both work wonders on either merieke or the creatures you take control of. there's also rare occasions i can go infinite with a Arcanis the Omnipotent and Mind Over Matter but that doesn't happen often.

also adding onto what Ohthenoises said, Dovescape and Guile is probably the most fun i've had winning a game.

Intruder Alarm

I've added both dovescape and guile and am STILL pursuing a Minamo (someone I know has one and is willing to part with it but for the last several months it has been at his home, over a hundred miles from campus).

I don't really need more methods to untap merieke aside from the land and what I already have, and intruder alarm would force her to untap which is bad. Arcanis and mind over matter are both good, although i think if i don't win upon resolution of the latter I will immediately die. I don't think time sieve would be good enough as it would require a specific card to do anything, and I always feel bad about setting an opponents life to a certain number (usually ten) as it is not balanced for the format, intended to halve a total, not quarter it.

Deathless angel and avacyn seem to be the next goal cards aside from the obvious and persistent Minamo.

a really good way to weaken the enemy is use Magister Sphinx, Desecration Demon, Divinity of Pride or Ghastlord of Fugue.

unhallowed pact, butcher of malakir, grave pact