MTG Salvation

That seems expensive; I mean, it's nice that commander tax effectively counts towards its X, but you're still spending 6 mana for a 3/3 that can temporarily bring in 2 additional power when it attacks? Even with high X values, the amount of ramp + sacrifice needed to make it effective seems like a lot of work for little relative value compared to other things you could be ramping into.

edit: oops, 6 mana is 6/6...that's definitely better; sorry for misreading

[edited because first version included overblown explanation of Mana math that others had already covered by the time I finished writing this comment]

I agree that you have to work at it a little but I think it's done pretty consistently with the right deck. you can maximize his power with cards like Xenagos, God of Revels or Overrun effects. Doubling Season of course gets slammed in, and sac-for benefit enchantments will let you make use of the tokens before they leave the battlefield.
It basically is a smashing together of Golgari graveyard decks and Gruul smashy decks.

MAybe a little bit of discard from Rakdos can help too.

Also, it's worth mentioning:
Master of Cruelties is an instant win if it goes unblocked. Gyrus does his thing, making a token copy of Master of Cruelties. Master of Cruelties, if it goes unblocked (Easy to achieve in EDH) reduces the defender's life to 1, then Gyrus hits for the win.

I think this is a goooood card and I might just have to start brewing for him.

Reread that ability. Even if x equals 0, this guy is still a 3/3.

ALL mana spent on this guy makes him stronger. Even the colored mana.

+1/+1 counters on it equal to the amount of mana spent to cast it.

It's p/t is not equal to X, it's equal to the mana spent to cast it. So 6 mana would get you a 6/6 that could reanimate a 5/5 or something.

edit: oops, nevermind

Not actually a good Hydra Tribal commander. Many Hydras will die as soon as this reanimates them.