Dashes Interacting with Grounding Abilties

Just a bit confused here. So 's Miasma ability creates pools of poison that ground enemies in it. 's slingshot allows him to launch himself over a distance. Now we all know LoL doesn't have any actual verticallity to it. Meaning if you use an ability that makes you travel in the air, you will still take the effects of whatever you're jumping over. Maybe it's just me, but whenever the we were versing would slingshot to us over 's miasma, he wouldn't even take noticeable damage. The Cass had a but the Zac didn't have the burn effect after flying over it. Also, does Cass's miasma not ground enemies that dash through it? It would be kinda weird for a grounding ability to act as a stun or root, stopping a dashing enemy in their tracks; but wouldn't that be the effect of a grounding move? I guess this whole thing hinges on the interaction of dashes through grounding abilities. Granted there's only 's Miasma and 's Adhesive as grounding abilities.