If Piercing Light targets a unit at a battlefield then a unit at a base, but the battlefield unit is removed (e.g., by Gust) before the spell resolves, does the base unit still take 2 damage?

Ruling: Yes, the unit at the base still takes 2 damage. The "then" in the spell text is a timing instruction, not a condition that requires the first target to still be valid.

Nuances:

• This ruling can be extrapolated from similar card interactions like Traveling Merchant
• The removal of the first target does not invalidate the second part of the effect