Does this dash/blink/leap/teleport apply to Rek'Sai Tunnel?
also, in the new BE store with the mini champion icons, can we know who is in the mystery pool? I dont want to drop 60,000 BE finding reksai if she aint there
Yep, Rek'Sai tunnel usage would trigger Sudden Impact.
Not sure about the blue essence store stuff sorry, I'm not very involved in that side of things.
I doubt it, its techinically just a movement (but faster) like 
E.
so i wouldnt say so but im not meddler :)
Rek'sai tunnel is a dash (as shown by it's interaction with poppy W), so any runes that interact with dashes would apply to rek'sai tunnels.
And would Hecarim devastating charge and onslaught of shadows trigger sudden impact?
Or maybe ghost
