I feel there's room for more Summoner Spells in the game. Let's brainstorm.
One mechanic that could be explored is displacement. I imagine a Summoner Spell that pushes away any nearby enemies. The name "Pulse" comes to mind. The primary use for this would be countering enemy engagements, but with clever positioning, could also be used to push enemies into your allies and their abilities, as well as disrupt enemy retreat.
"Pulse" would be useful when facing enemy Assassins, and Supports could take it to respond to ganks from the enemy Jungler or midlaner. I think Yuumi in particular would be a good Pulse-user.
Any thoughts on my Summoner Spell? Or if you have a Summoner Spell design you'd like to share, please do.