I cast a Clown Car, while I control Omarthis, Ghostfire Initiate. Assuming I crew the vehicle before the ETB trigger resolves, will Omarthis get a counter for each counter Clown Car gets or just one if Clown Car gets one?
My gut says just one counter, however Cascade and Laelia has told me that one effect can generate multiple instances so I'm unsure with the exact wording.
Just one.
Clown Car's triggered ability is a single instance of token creation and a single instance of adding +1/+1 counters to the vehicle.
In general, effects that do something "for each" of something are just a single instance of that action happening that scales. (The only exception is with weird cards like Tempt with Discovery that have to work differently because of their templating.)
