I can deal with the change to Veigar's E if this extra feature is added to the stun
Make enemies that attempt to dash through the walls of the stun get stopped at the walls instead of completing the full distance of their dash. This will allow for a more defensive use of veigar's stun, dropping it around himself and his team's carries to help him fight against the LBs, yasuos, dianas, who can currently 1 shot him if he misses his stun on the live patch. Since the purpose of the delay is to give enemies a chance to react to what is currently an instant AoE stun, give it more defensive utility since the delay weakens its offensive strength. tl;dr, make it so enemies that dash through veigar's stun cage stop and get stunned at the point they contact the cage instead of dashing all the way to the dash's targeted location.