Does it matter whether a card targets or not, and do Snapvine and Last Breath target differently?

Ruling: Whether or not something targets determines if you need to select targets as you put it onto the chain. Last Breath should target both the friendly unit and the enemy unit.

Nuances:

• Targeting is currently ambiguous in the rules and under discussion
• Generally, if a card has you select/act upon an object from some set of possible objects (instead of acting upon an entire set of objects), it targets that object
• Cards with "Then" in their text (like Dragon's Rage) create additional ambiguity about what they target
• Snapvine targets and also says "a" battlefield not "this" battlefield, so you play it to your base and it fights a unit at a battlefield