armor makes it unusually good. also, there is no petrify duration for death effect (could be permanent, 5 turns if like basilisk, 4 turns if like stonemage).

Oh, yes, you're right about the duration being unspecified. My fail... Usually I make sure to include that kind of thing, don't know why/how I didn't here.
I think the biggest mistake I made with that piece is adding the Petrify on melee death bit, actually. ...but it was just so boring, so I was attempting to make it more interesting (which I don't think succeeded at all).

hopefully destroy is magic so no hostage thing goes on. hard to use since it only gains fake bomber passive if it uses the diagonal ability.

Yes, I should've put "(Magic)" in front of "Destroy"... Though, in my defence, none of the "Immune to" passives say it.
I didn't want to make it Destroy its melee attacker, as that would've been too strong (or Destroy the unit in the next space in the direction it moves), but you may be right that it is too weak as it is. However, it is immune to (Magic) Destroy and effectively immune to Freeze, so I don't know that it is that much weaker than FrostMephit.