The cc-effect "grounded", that disables all movement skills does not apply correctly to jarvans e+q combo. Jarvan can use this dash while standing on cassiopeias w (miasma). (And jarvan's e+q is a dash, because it is also blocked by poppy's w)
Timethief493 votesThe thing is grounded stops movement abilitys from beeing used. Neither e or q by itself is a Mobility skill. Poppy w stops a champ while using a Mobility skill.
Sahn Uzal2 votesYou should read the tooltip on his Q, it specifically mentions ''This effect can be triggered while immobilized''
