This game needs a Story Mode.

It might take a long time to create something of the like, but I feel that it would be totally worth it.

I think this could make the different lores much more appealing since champion lores aren't given much attention nor well-displayed, and players normally need some random incentive to become curious about a champion and even have to do a little "digging" in order to learn each of their stories. In addition, this could make the game much more interesting, interactive, or even fun. Players who are new to champions could simultaneously learn and practice the champion's abilities as well. A champion's story cannot be played unless bought, of course.

The story modes should surround each champion's current lore from beginning to end. They don't have to be long nor difficult.

For example, in starting up a story mode for Master Yi, there could be some textual introduction to Master Yi's lore accompanied with several images that pertain to the progressing context. Then it would transition to Noxian soldiers standing in front of Master Yi in the middle of a burning village or something. At this point, Master Yi's abilities are introduced and you are able to test them on the Noxian soldiers. After defeating them, you tread on, fighting Noxian soldiers along the way. At the end of the path, Master Yi would end up at another part of the village, seeing some dead villagers and Singed's poison gas all around. In the middle of the poison gas, you see Singed appear laughing as the poison affects Master Yi, resulting in him fainting. This would then transition to another scene full of texts and images about Master Yi's vengeance, training, and encounter with Wukong, who could serve as some sort of "final boss" to Master Yi's lore post-scene. The ending scene would conclude the lore with some more text, and the player would end up at a results screen.

Although some champions may not have a lore that suggests any sort of combat, there is always room for creativity.

Should the story modes have any sort of reward? I'm not sure. Maybe, I guess? Probably minor hextech stuff? Maybe less IP/EXP than what you usually get in an actual game? Only a reward for playing the first time (assuming it's replayable)? Idk. I can't really say since I have no stance on whether or not it's a good idea. But I can definitely say that I think that having a story mode is a great one.