Heh. An 11-mana 0/1 is funny, but given Broodstar this could probably have some P/T itself. Either something like 6/6, or perhaps */* like Broodstar or Master of Etherium?

Given the cards in my other sets, it's possible to get 8 artifact creatures on the field on turn 4, playing this on turn 5 basically means your creatures have annihilator 8 on that turn.

Think of it this way, this says:

Cost:8WRB-X

When you attack, defending player sacs X permanents

Give it too much toughness and this will be impossible to deal. Plus, Shabtis are all 0/1's, since they're intended to be clay puppets that are easy to break and are made to enhance other people (like a bard)

hell, it may be possible to get 8 artifact creature (even 1/1s) on turn 3. With no answer, making people sac 8 permanents is pretty backbreaking. That's why it's a mythic.

It also means that even a Spark Jolt can deal with it, so there's that downfall.