Maybe try Demon of Death's Gate as a heavier creature, and maybe consider Doom Blade or Murder as some cards to just quickly eliminate the enemy creatures. Also maybe Bojuka Bog and Crypt of Agadeem as they may work well with your deck.

28.4% chance of drawing the stone, or a tutor needed to find the stone, on turn 1. By turn 6 it is game over. Not very solid, or practical, or sensible I know, but this deck was meant for a laugh so please don't hate or comment what is blindingly obvious, e.g. "needs more reliability" etc.

Think about Coat of Arms.

thanks JinRocker, however coat of arms could potentially buff my opponents creatures as well as my own, which is undesirable. Also, it basically does exactly the same thing as having an additional relentless rat on the board, but for 5 mana instead of 3. Thanks for taking the time to have a look though!

What about Swarmyard

thanks! Great idea!

I think that this deck will become boring very soon as the games will be always the same. Try more cards that fit the theme like Desperate Research, Ratcatcher, Cursed Scroll or Twinning Glass

Mr_Sam I hear you, however the main idea of this deck was just to have laugh at the expression on your opponents' faces when you whack down the thrummingstone. I most likely will not be actually playing it regularly - but it is a nice wildcard to shut a smarmy mate up or to prove a point (e.g. Tribal Rats are the ultimate wincon). However, thank you for taking the time to comment :)

Tendrils of Agony is a great card along with Thrumming Stone.

Beseech the Queen and Brainspoil for additional tutors

nosoyyucateco does Tendrils of Agony work with thrummingstone? Thrummingstone says you can PLAY them, and The tendrils specifies that it is each spell CAST before it. I am by no means a judge, so I was just curious as to this matter. However, if it does I will be sure to add it in.

Ulvhedner thanks!

Thanks for the comments :)

Yep, it works. Thrumming stone away, then top it off with Tendrils of Agony for the win. Since the spell is copied, even if they counter it they are only countering one copy of the spell. Playing your Relentless Rats with Thrumming Stone counts as casting a spell, so your storm counter will get very high with this deck.

Also, I second Beseech the Queen. Brainspoil is not a bad idea, though if you already have your Thrumming Stone it is essentially a dead draw, since you only have one card here with a CMC of 5. The nice thing about transmute is that it can't be countered though.

Play and cast are synonymous. For reference:

http://www.mtgsalvation.com/forums/magic-fundamentals/magic-rulings/567954-play-vs-cast

Another variation of this deck, by the way, uses Shadowborn Apostle instead of Relentless Rats.

Then you can include a Rune-Scarred Demon for a tutor with all your Shadowborn Apostles. Sorry to spam your deck like this. I just like this idea for a one-off "screw you guys, I'm going home". Because nobody will ever want to play against this deck again in EDH. XD

If you do happen to draw Brainspoil after you've found Thrumming Stone, nothing will prevent you (except counterspells and myriads of other things) from casting it to destroy something. So it's not useless.

For other tutors there's also the more expensive Grim Tutor, Imperial Seal, Cruel Tutor, Diabolic Intent, Demonic Collusion, Insidious Dreams, Liliana Vess and the somewhat questionable Rhystic Tutor

Thanks guys, and haha I don't mind if you comment, advice is great! Also, thank you for clearing up the whole cast/play shenanigan. Also, this deck originally did run half shadowborn apostle half rats, however I decided that I needed to pick one of the two and the rats are simultaneously more outrageous and yet more fun to play in my opinion - Tribal Rats EDH! Who would have thought?

Also, Ulvhedner I do not want to include many/any more tutors in this deck, as with the ones I currently have I am almost guaranteed to get the thrummingstone in hand by turn 5. However, thanks for the ideas - I may swap some of the slower/dodgier tutors out at some stage.

Thanks guys!

Don't you just end up milling yourself out before you can attack.

MooneBoyIrish: Thrumming Stone puts all cards that aren't cast using ripple on the bottom of your library, which means that I will have 35 or so swamps in my deck after the stone has synergised with the rats. Also, Maralen of the Mornsong shuts down any sort of mill (including self-mill) as players can't draw cards. From an empty library or otherwise.

Soooo... strategy for dealing with Wrath of God ?

You don't have haste, sooo: Wrath of God, Damnation, Rout, Chain Reaction, End Hostilities, Phyrexian Rebirth, Terminus, Supreme Verdict, etc., etc.

Someone I know is making a Relentless Rats EDH and it just gets shut down so easily that it doesn't seem like it's all too powerful against any deck with board removal capabilities, which is any good EDH deck.

I do see what you mean, and have been aware since the beginning of this deck's (many) weaknesses. However, it was never really meant to be highly competitive, more a one-off hit to surprise an opponent. Besides the boardwipes, this deck also takes 5 turns before I can combo out so it's fairly weak anyway. If anyone can think of any suggestions that will give my rats protection/haste or that will give the deck more consistency, please share!