Nah, this is neutral, not Songhai.
New neutral unit concept: Boulder Breacher
wait there a second … THIS GUY IS A MACHINE!
what if this is Mechaz0rd related? or simply a new mech?
“Attacks by this minion ignore effects that reduce or prevent damage.”
Sunsteel Defender’s ultimate foil. Among other things.
Uhm… “Nose” of Mechaz0rd, if we want to keep it kids friendly.
A minion like this is OP, how can you damage it when it is underground?
more credible The idea that it can move througs enemies.
I think AoE and AoE dispel should be able to affect it. Just like HS.
You can’t damage it, that’s the idea. But maybe there should be another neutral minion out there who can hard counter it. Something like:

Deals double damage to enemy units that can’t move. The ultimate demolition expert that can take down any wall, obelisk, or rok.
or it could ignore forcefield, or even remove spellshields
Enemies he kills explode dealing aoe damage to surrounding minions
or
he gets first strike when an enemy attacks him
When this unit attacks, inflict 3 damage to all enemy units in the front row of this unit.
So when this attacks a forcefield unit head-on, the field goes down and bye bye sunsteel. The attack is so powerful that all infront units of the same row gets damaged.
Reality Breacher
9 mana 13/13
Dying wish: summon Galaxy Breacher
Galaxy Breacher
6 mana 8/8
Dying wish: summon Star Breacher
Star Breacher
4 mana 5/5
Dying wish: summon Planet Breacher
Planet Breacher
2 mana 3/3
Dying wish: summon Mountain Breacher
Mountain Breacher
1 mana 2/2
Dying wish: summon Boulder Breacher
Boulder Breacher
0 mana 1/1
Dying wish: add Reality Breacher to your hand.
A mech inside a mech inside a mech inside a…
Inside a what?
Inside a digital collectable card game?
Backstab, Forcefield, Provoke.
Maybe … dispel Provoke or Forcefield units when he attacks it while taking no damage in the process ? That’s my guess. 
Gurenn Lagann anyone ?
sure, I mean, look it even has the drill
3 mana 3/3
Deals 2 extra damage to unbuffed units.
I think it can pass through units, and deals 2 damage to units it passes through
Wait, how can the drill pierces a hole large enough for the arms to get through?
It is not even as large as the torso.
It could also be:
can move throug walls. Deals 3 damage to any wall card it goes through, to counter the omnipresent walls in the meta.