Miraidon, Iron Serpent

Haste, Hexproof
Whenever Miraidon, Iron Serpent attacks, you
may put an artifact or creature card from your
hand onto the battlefield, if a creature card is put
onto the battlefield this way, that creature enters
the battlefield tapped and attacking.
This seems to be the Iron Serpent mentioned in an old
book. The Iron Serpent is said to have turned the land
to ash with its lightning.