Rust Goliath

Prototype {3}{G}{G} — 3/5 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Reach, trample

Construct

This creature gets +1/+1 for each artifact you control.

Pyrewood Gearhulk

Vigilance, menace
When this creature enters, other creatures you control get +2/+2 and gain vigilance and menace until end of turn. Damage can't be prevented this turn.

Darksteel Colossus

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Indestructible (Damage and effects that say "destroy" don't destroy this creature.)
If Darksteel Colossus would be put into a graveyard from anywhere, reveal Darksteel Colossus and shuffle it into its owner's library instead.