See Wellpoisoner Snake.

So the imagery here is a creature that snores everything to death?

Oh; it's got an 'other' in there. That's a shame. As a one-shot threat this is probably fine. Hanging around as a permanent board sweeper? Not so much fun.

To be fair, this is a direct colourshift of Crypt Rats except adding the word "other".

I don't think the addition of the word "other" justifies making this mythic, btw. Certainly not as a 4-mana 1/1.

Sloths hang out in trees so the sloth is immune to its own earthquakes. The show has uses about as much science as alternative medicine, so just roll with it.

The repeatability due to "other" felt mythic. The 1/1 pt is because it's regular sloth and not a ground sloth. I mean maybe those claws can wreck stuff, but 1/1 feels right. I just didn't see the ability being on a body less than 4 drop. The mythicness of some of my designs has been questioned and I must admit that I don't always understand why Wizards makes certain cards mythic instead of rare sometimes.

I love the name.

I'm not actually sure about the strength. It's expensive definitely, so maybe not mythic. But allowing a repeatable wrath is potentially v strong.

I generally judge what makes a Mythic based upon 'Wow' factor more than anything else. When a person opens a pack and looks at this card, will their immediate reaction be "Oh! Cool!" What if they're an experienced player? What if they are new to the game?

That said, one thing that I would almost automatically disallow from being a Mythic would be a card that includes a restriction, unless the restriction itself is somehow 'wow' worthy (see also: Abyssal Persecutor.) Earthquake Sloth is restricted to the use of Mountains only, which, in my mind, makes it a rare.

If, however, you wanted this card to be Mythic, I don't think it would be hard. Simply increase the casting cost, remove the 'Mountains only' restriction, and jump the power and toughness to be equivalent or almost equivalent to the casting cost. Let's say a 6/6 for that is unrestricted in its ability to keep smashing the sky. That should get some people's attention (I'd probably remove the two words 'each other' as well. Remember, in my version of an ideal Mythic card, you want to go for impact. Every extra word you add cuts into the striking gut punch that is this card's ability.)

Setting all that aside: I can't remember how your other designs play out off the top of my head, Sorrow, but if they're anything like this card and your comments in this thread, than your design is very top-down-concept-first. My argument for what makes a good Mythic is a very bottom-up-mechanic-first argument. But I still think the whole point is to 'wow' someone, even when going top down. You just need to find out what makes your story/card special and drive down on it like a hammer on a spike.

How relative is "wow"? A repeatable wrath-like effect was "wow" to me. Neither Deathmist Raptor nor Sphinx's Revelation evoked such a response, yet both were important mythics.

I'm a bad judge of power, usually nerfing things hard. The restriction to red mana was such a nerf.

I think the important thing is that someone is saying 'wow'. Sphinx's revelation looks pretty ho-hum for someone who's looking for an exciting line of text. But if you've religiously been using Blue Sun's Zenith to draw cards, the ability to gain bonus life for relatively little effort is a game changer.

Really, it depends on the player. Every mythic must be exciting. But you shouldn't try to make mythics exciting to every player. Similarly, a movie or television show that everyone says they like is bound to be pretty boring. As far as I'm concerned, mythic takes risks.

Now whether or not the power level of this card is acceptable is another argument all together. I'm not sure. It's incredibly powerful, but you're still restricted by X, will only hit a subset of cards, and its got a small body. Maybe it is fine? One thing for sure, though, is that a card like this is bound to make some people who are drinking their morning coffee spit their drink back out. It's bound to get people arguing. I like that kind of mythic more than the cautious type that people tend to forget about.

Yep, now that this isn't restricted to red mana, this is probably "wow"-making and mythic-worthy.

Whether it turns out to be fun in play is a different question.