Okay, so for starters I would definitely try to get the card count down to 60. The reason most decks are 60 cards, no more, is the fact that with fewer cards, you have a better chance to draw the cards that you need. Usually you want to go with between 22-25 lands, and the rest of the cards for whatever. I'm going to go ahead and assume you want this to be a Standard(Type 2) legal deck. You can get information on the different deck types at this web site http://en.wikipedia.org/wiki/Magic:_The_Gathering_formats. That beind said, I would probably cut the following cards to bring it down to 60.

Scab-Clan Giant : this card looks really good on paper. However the major problem with it is that you can't choose the target.

Tibalt, the Fiend-Blooded : Probably the worst plainswalker in the existance of ever. His +1 ability would be useful if, as with The Giant, you could choose the card to discard. His -4 ability is lackluster as people won't be keeping cards in hand if he his on the field, also you won't really get more then a couple damage with it anyways. And his ultimate is only useful in very certain situations.

Ruination Wurm : The biggest problem with this is the card has no abilities. I would consider keeping it if it had something, maybe trample.

Primal Visitation : The problem with this is that you won't really ever play it on something and get the benefit of the haste due to it have a mana cost of 5.

Another thing to note is that for most of the core of your deck you want to have 4 copies of each card. Take a look around here and (With the exception of EDH) you will usually see a deck that has exactly 60 cards in the main deck, with a 15 card sideboard, and 4 copies of just about every card.

Hope this helps! Feel free to take a look at my Return to Ravnica block Gruul deck if you would like some ideas. RTR block Gruul

Lets see here, most of the tweaks look good, I'd probably cut the Boundless Realms for a couple more Armed / Dangerous . For competitive play, Gruul Ragebeast , Borborygmos Enraged , and Zhur-Taa Ancient are a bit slow. Zhur-Taa Druid can be easily replaced by Arbor Elf . I'd definitely look into putting in Madcap Skills , as well as possibly Rancor . Also you could really use some type of targeted removal/ burn a-la Mizzium Mortars or Searing Spear

I've played my Gruul deck probably 15 times, and I shuffle and sometimes I think that I am cheating without realizing and have someone cut my deck or even them shuffle but I always get lucky enough to have enough mana and small creatures and normally get Domri Rade very quickly, so I figured I could cut out some Armed / Dangerous since I always get my creatures to have double strike, trample, hexproof, and haste. I do think that Madcap Skills better than Primal Visitation since it cost 5 mana and gives +3/+3. So I can definitely use a couple of them, Do you recommend anything to destroy a creature that is indestructible? That is my biggest issue so far when using this deck. I like Zhur-Taa Ancient for the ability with the mana, speaking of which I don't know if I am using that ability correctly. I don't understand if my mana keeps counting up by one each time I use it or if it is a one turn thing. I dunno, kinda throwing me off. I could probably get rid of Boundless Realms I just have it in their currently for extra mana but with the creatures I have that add mana help out so it is kinda pointless thinking about it. What I really need is more people with different decks and different strategies to play against that aren't worried about it being up to date. Just a friendly competition or whatever. My main goal for this deck is to have all creatures Gruul colors. Multi-Colors no Mono-Colored and I might even cut out Chandra, the Firebrand to keep everything besides mana a complete Multi-Colored deck.

Everyone seems to overlook the Lure effect on Armed / Dangerous . You cast the Dangerous portion on a creature you don't care about losing and then everything else you attack with will get through, guaranteed. Also you can use the Armed portion well before you will have ulted Domri. Plainswalkers almost always become Priority target #1 as soon as they hit the field.

Zhur-Taa Ancient works as follows. Assuming he is on the field and you tap a Forest , instead of getting one Green mana, you get 2. If you tap a Rootbound Crag You would get either 2 Green or 2 Red. One of the major drawbacks of the Ancient is that your opponents get to use it as well, so it can be a double-edged sword.