Zac's Q can be blocked by Pantheon's passive

Zac Q can be blocked by Pantheon's passive. Zac's Q is not an auto attack, does no physical damage, and does not apply on hit effects and should not be blockable by Pantheon or any champion with a block effect (Teemo, Jax, Shen).

The below video shows Zac's Q working and not getting blocked when the first cast of Q hits Pantheon, then shows Zac's Q getting blocked when the second cast of Q hits Pantheon (I used stretching strike twice in this video). https://www.twitch.tv/videos/151582761