Tarmogoyf

This is an okay card. I mean, it's no Cognivore, but it'll do in a pinch. It's a fast drop and it can get fairly powerful, but it has some problems. 

First off, there are ways to get rid of it. Good cards have no way to actually get rid of them because, if they did, they wouldn't be good. That's why cards like Norin the Wary and Progenitus are the best cards in Magic. This card has a bunch of different way to deal with it: Doom Blade, Terror, Unsummon, Vindicate, Bazaar of Wonders, and Threads of Disloyalty to name a few. If you've got a permanent that can end up in your graveyard somehow, it's a dead card because you're just going to waste mana casting it just for it to be destroyed.

Second, it has no evasion. Cards like Aven Envoy and Zodiac Rooster are better because they have some sort of evasion at least. Cards with no evasion can easily be blocked and therefore have no point in swinging, even if the opponent is going to lose a creature or two. They could have some sort of buff spell in their hand and it's not a good idea to risk losing your creature to some Typhoid Rats with Daring Leap cast on it.

Thirdly, it's not a relevant creature type. There's absolutely no support for "Lhurgoyfs" outside of the generic cards like Coat of Arms and Door of Destinies. If you don't have the tribal support for something, it's just going to stand out there on its own with no help from anything else. It won't synergize with your deck at all and you might as well be running other random cards that don't interact with anything else in your deck like Putrid Lecch or Xantid Swarm.

Finally, while this card can grow, it has a power cap. At best, this can be an 8/9 whereas something like Boneyard Wurm can be much bigger depending on how many creatures you have in your graveyard and Kodama of the Center Tree, which is dependent on the number of Spirits you.control. Also, to ensure that you're getting the most out of this card, you'll have to overload your deck with a bunch of different types of cards and make sure they end up in your graveyard.

 All in all, an alright card if you've got the spot.

Pros: Fast drop, can grow over time

Cons: No evasion, dies to removal, not a relevant creature type, power cap

Rating: 1.5/5

See how stupid some of these "that's not a good card because x" arguments can be? Seriously, this card is great. 5/5.