It isn’t a goal to add new spells in the same way it is a goal to add new champions. We would rather have a smaller set of summoner spells that get a lot of play and have interesting and exciting uses than a huge stable of spells that isn’t that exciting. Spells like Flash and Teleport can be game changers. Things like Exhaust and Ignite are fairly interesting and do get used, but they aren’t the source of big plays like Flash and Teleport are. We’re okay with that space as long as they are relevant. Barrier and Clarity often do struggle to be relevant, but they can still be a good choice, in the right circumstances. And of course, we have pruned some spells over time that just weren’t that interesting (and didn’t feel like they had a lot of options to make more interesting).

So it’s possible someone will come up with a great idea for a new summoner spell, but it would have to be a really good one that could compete with the ones we have today.