Can a player cast Defiant Dance when their opponent has Ruin Runner (which prevents targeting), if they have two of their own units to target?

Ruling: You must select valid targets for Defiant Dance. If you cannot select an opposing unit due to Ruin Runner and have no other valid targets, you cannot play Defiant Dance. However, if you have two of your own units, you can target both of them instead.

Nuances:

• Defiant Dance requires two distinct unit targets to be played
• The targets cannot be Ruin Runner itself
• If valid targets exist (such as two of your own units), the spell can be played even if the opponent's units cannot be targeted