Mechios, the Demonic Golesmith

Hexproof, trample, protection from instants
{3}{t}: Gain control of target artifact.
Whenever a nontoken artifact enters the battlefield under your control, create a treasure and a colorless 5/7 construct with hexproof and trample.
If you control 5 or more colorless 5/7 constructs, Mechios, the Demonic Golesmith gains indestructible.