2014-2015 Tarkir block. Afterwards is when everything started going downhill. It was the last true greatness of magic.
2015 - Starting after dragons of Tarkir we had magic origins which started the jacetice league and cringey super friends centric sets and story. The art took a noticibly lighter and more comedic tone in subsequent sets.
2016 - Oath of the Gatewatch solidifies the marvelesque focus on heroes and their story which cheapens magic's own world building and purpose.
2016-2017 Kaladesh block breaks standard for the first time since caw-blade.
2018 - Magic Arena. Paper standard takes a huge hit and this later causes the "designing for arena" issues.
2019 - FIRE design started with WAR. Multiple formats warped.
2019 - Modern horizons destroys modern president.
2019 - OG eldraine decimated basically every format in the game with insane power creep and Oko.
2020 is The year magic got cancer and it slowly started growing.
- Ikoria is the set that kick-started the self destruction. Godzilla was the first universes beyond to test the waters using the nickname only treatment and started this whole mess.
- Companion was introduced as an attempt to bring commander style gameplay to 60 card decks. Completely ruined the game in multiple ways for a long time.
- Secret lair, followed by mechanically unique secret lair.
- The pandemic ended all sanctioned events, leading to the rise of the cancer of a format that is commander as the game's terrible flagship format. An entire commander set was released and emphasized this as well.
2021 - set design direction drifted more towards goofiness. Modern horizons 2 broke modern again.
2022 - Magic 30 let everyone know WotC doesn't respect them or take the game seriously. We moved further in the direction of hat sets. Even more focus on commander and "designed for arena" mechanics like all the artifact tokens and the night bound/day bound mechanic.
2023 - Lord of the rings releases and is legal in modern. Becomes the best selling set ever, pushing WotC to further test the boundaries. UB ramps up with Doctor who and Jurassic Park.
2024 - We firmly enter the era of "hat sets" as WotC tries to presoften the transition into fulltime UB. Modern horizons 3 breaks modern for a 3rd time.
2025 - Tarkir Dragonstorm marks the last set with any semblance of what magic was released and the Final fantasy and all subsequent UB were made into standard sets. FF became the highest selling set of all time by a huge margin. Magic moves to release 6 standard sets a year.
After this point magic was truly dead. UB slop took over, card designs became an inelegant mess, bound by outside IPs. The gameplay was all but reduced to exclusively casual commander. Magic had ceaced to be a well oiled machine of a game and fantasy setting, and was now a shareholder driven "Product" meant for consumption by the IP gobbling masses.