No man is an island. Except if you are playing top lane, then you most definitely are, and if you are on the losing end of any trade, in the lane, you can expect to be useless for the rest of the game, basically.
Most matchups will be forced to run Lethal Tempo into each other or they risk getting stat-checked by the absurd attack speed steroid that Lethal Tempo is giving from the get-go. Tanks will not function at all. Period.
Irelia already has more base range than all the top lane melee champions. She already has a strong attack-speed steroid on her passive. Putting these two with Lethal Tempo is a recipe for disaster and knowing Riot, we wouldn't want them to end up nerfing Irelia or other champions like Jax over it.
Darius, for example, will be able to level 1 cheese incredibly well, especially after the recent CD buffs to his W. This time it will be far stronger and will probably 100% guarantee a flash no matter what thanks to the extra AA range.
Also, the edgy brothers, Yasuo & Yone will have almost nearly, a full CDR on their Q. You may ask yourself, how do you trade with that exactly? Well, so do we. How does anyone have any capabilities of fighting them when they're getting knock-ups off so quickly?
Riot Games
Adding to all of this, one of Gwen's primary issues before her nerfs was the attack speed she got from her E in the early game. Seems like those times will return, thanks again to Lethal Tempo.
It seems like this will be the repeat of what happened in season 9 when the team with the most Domination runes almost automatically won. Hopefully, Riot will see the problem as soon as possible, and resolve it in a satisfactory manner. Or they will just nerf Aurelion Sol.
