If Spark Double enters the battlefield and copies nothing, does it get a +1/+1 counter?
The text does say "except it enters with an additional +1/+1 counter if it's a creature", but that clause follows the clause "You may have Spark Double enter the battlefield as a copy of a creature or a planeswalker you control". So I was thinking the former clause might only apply if it actually copies something.
The ability is linked to a may clause, and it is all one ability. So if you choose to not target anything, you are choosing to not resolve its etb effect. Part of that effect is the +1/+1 counter. So no it will not get a counter unless it copies something.
The text does say "except it enters with an additional +1/+1 counter if it's a creature", but that clause follows the clause "You may have Spark Double enter the battlefield as a copy of a creature or a planeswalker you control". So I was thinking the former clause might only apply if it actually copies something.