you can, the starfall visual stops and u don't see the dmg ticks, but the dmg and the visual appears again once the mage stun ends.
If u focus on starfall visual, it stops for like 3s to 4s and then it keeps going
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Starfall doesn't do any dmg till the 3/4s of mage stun are gone, u can see it clearly in the video, the visual of starfall appears like 4s after he used it due to the mage stun:
https://www.youtube.com/watch?v=UqG_piLGja0&feature=youtu.be
starfall 6s before he gets under mage stun (check dudu buffs)
http://i.imgur.com/xSVNGFs.jpg
Starfall visual appears after 3-4seconds, you can count it:
http://i.imgur.com/tdTWXDz.png
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https://www.youtube.com/watch?v=smv4EpnS09s&feature=youtu.be
the dudu has starfall buff before getting stun, but we don't see any dmg/visual till 4s, which is the duration of mage stun.