Hulking Metamorph

Any enters-the-battlefield abilities of the copied permanent will trigger when Hulking Metamorph enters the battlefield. Any "as [this] enters the battlefield" or "[this] enters the battlefield with" abilities of the chosen permanent will also work.

Casting a prototyped spell isn't the same as casting it for an alternative cost, and an alternative cost may be applied to a spell cast this way. For example, if an effect allows you to cast an artifact card without paying its mana cost, you could either cast Blitz Automaton normally, or as a prototyped spell.

If the chosen permanent is copying something else (for example, if the chosen permanent is a Clone), then your Hulking Metamorph enters the battlefield as whatever the chosen permanent copied, with the stated exceptions.

You can choose not to copy anything. In that case, Hulking Metamorph simply enters the battlefield as a 7/7 (or 3/3) artifact creature.

The prototype ability functions in any zone that the spell could be cast from. For example, if an effect allows you to cast artifact spells from your graveyard, you could cast a prototyped Blitz Automaton from your graveyard.

When cast as a prototyped spell, that spell has the mana cost, power, and toughness characteristics shown in its colored, secondary text box rather than the normal values of those characteristics. Its color and mana value are determined by that mana cost. The permanent that spell becomes as it resolves has the same characteristics. If the spell leaves the stack in any other way, or the permanent it becomes leaves the battlefield, it immediately resumes using its normal characteristics.