If the only enemy unit has deflect, must I choose it as a target when I play Blitzcrank at a battlefield?

Ruling: Yes, you must target the enemy unit with deflect when playing Blitzcrank, even if it's the only enemy unit. However, you can decline to actually move the unit when the effect resolves.

Sequence:

• When playing Blitzcrank, you must select a valid target (the enemy unit with deflect)
• This triggers deflect's power cost requirement
• On resolution, you may choose not to move the unit (declining the "may" effect)
• You will not get back the resources spent on deflect's cost

Nuances:

• The "may" in the effect text refers to the optional nature of the move on resolution, not the targeting requirement
• You must have valid targets to play the card, but can decline the optional effect when it resolves