I was in a match, playing as Kog'maw, recently. After dying, I tried to kill an enemy Sivir using my passive which explodes and does True damage to the enemy. Sivir blocked my passive explosion using her built-in spell shield ability. Are there other passives, such as Ziggs' or Nautilus' that can be blocked by spell shields? I think that these skills would be good for bringing the enemy's defenses down as a team fight starts, so that you can hit through their shield to do more damage or to poke more easily.
In short, you can and should try to deactivate the other team's banshee veil if you can before the teamfight starts. This is best done with spammable skills to poke like Ashe volley. However, there is nothing you can do that forces a player to utilize their active when they don't want to, for instance Sivir's spell shield, Nocturne's spell shield, zhonya's hourglass active to name a few.