Mirage Tornado affects players in viscous cube even with T2 upgrade.

[Tides]

Expected behavior: Players in the cube should not be affected by the tornado. Specially not with the dispels all debuffs upgrade.

 

[#1 Cool Veno Appreciator]

From what I recall, the cube purges debuffs, it doesn't prevent new ones from applying. You can be stunned in the cube by, for instance, an Infernus ult. It'll prevent you from ending it early. However, if you cube a stunned teammate, they immediately get un-stunned.