Can Blitzcrank, Impassive be played to a battlefield to trigger his ability, or must he be played to your base?

Ruling: Blitzcrank can be played to a battlefield you already control, which allows his ability to trigger. He can also be played to a battlefield using external effects like Miss Fortune, Buccaneer.

Nuances:

• You can play units to battlefields you already control
• This is the usual way to use Blitzcrank's ability
• External effects that play units to battlefields also work