A ton of changes to the game happened over the last decade. Some of them, quite a few years ago.
Summoner’s Rift remake
For example one of the biggest changes made to League of Legends, was the remake of the map itself. Summoner’s Rift received a graphical and technical update on May 23rd 2012 and then remade completely on November 12th of 2014.
Ultra Rapid Fire game mode was first released in 2014 as an Aprils Fool joke.
There was an old system that had players buy runes for IP (now blue essence) to customize their strengths before the game. You could choose from a variety of runes which slightly made you stronger in various aspects of the game. Ones made you faster, others made you tanky etc. And some, gave you a chance to crit at level 1 and demolish your lane.
This rune system was completely removed in patch 7.22 - November 8th, 2017
Deathfire’s Grasp, the original
The original Deathfire’s Grasp was introduced into the game on October 1, 2009. And removed shortly after. After a bit of rebalancing, it was again added to the game on December 2, 2009.
It was being adjusted and balanced for many years, before it received an icon update on July 30, 2013. But it seemed that this item still posed a lot of headache to the balancing team, as it was removed again two years later on January 28, 2015.
A few years passed and Deathfire’s Grasp was added to the game again on August 15th, 2018 as part of the experimental Nexus Blitz game mode. And removed on January 9th, 2019.
Then once again added to the game on July 22nd, 2020 and removed on August 24th, 2020, since Nexus Blitz was removed also.
Rift Herald was introduced to the game on November 11, 2015. It was met with quite a bit of mixed reception. Some loved it, some hated it dearly. At the very start though, it was a bit different. An objective to fight for on the top side of the map, but it wouldn’t spawn Shelly as we know now, it would just give you a mini “Baron buff” to let you push the lanes easier.
Mana Potion was in the game from the first pre-alpha versions of league of legends and then removed on November 11, 2015. It was re-added to the game on November 8th, 2017 and again removed on November 20th, 2019. Seems like for good this time. A lot of people miss this item.
Jungle Plants were one of the most controversial changes to the game when first announced. People were really scared it would change the game drastically and introduce a ton of RNG to the games. But with time, people learned that you can play around them and they became a huge part of league of legends. They were added to the game on November 10th, 2016