playing a match sometime ago was up against a ziggs things were going well till top lane jarvan came to my lane and double teamed me with ziggs I was thinking I could handle but little did I realize that miasma is not doing what it is supposed to do....shortly after that jarvan got in close ulted and chained ziggs ult and I lost the lane for about 5 min due too a double mid. [zombie-brand-facepalm]
Jarvan dash ignores all crowd control if he's able to cast Q on a flag. It isn't a movement spell in the traditional sense and even the tooltips mentions it.
Jarvan's isn't a mobility spell technically. It just causes mobility. Grounding doesn't prevent mobility, just prevents mobility spells from being cast or you'd have champs like LB cast W and have it go on CD and use mana, but not go anywhere. With this in mind, we look at Jarvan's pull. Miasma can't stop the flag cast because it isn't mobility. It can't prevent Q being cast because Q is simply a linear skillshot. But, the coding has Jarvan pulled to the flag if the linear skillshot's hitbox hits the flag's hitbox. So, it evades Miasma because it wasn't a mobility spell, just an interaction. I'm fairly certain Ziggs is the same with his satchel charge.
Miasma should stop Jarvan from ulting because that is a mobiility spell. But only from it being cast, not mid ult. The pull I believe is entirely exempt though since there is no mobility to be cast.
It sounds like he passed through the miasma mid-dash, and I'm not exactly sure if that spell stops ongoing dashes, I don't see Cass enough to see that.
It's like people taking thresh lanterns - it hauls the champ away rather than the champ doing a dash move
Is 
's spear toss not a mobility spell by the same game-logic?
I've never seen those two against each other to know.
