Lethal tempo
I love the concept of lethal tempo, to break the limit of the attack speed is definitely an awesome way to fight. However, lethal tempo has been the least used runes in both professional matches. Due to this lethal tempo might get removed, I'm quite worried and do not wish this to happen. Therefore I post some possible adjustment and hopefully it will helped.
original version: lethal tempo: PASSIVE: Damaging an enemy champion begins a 1.5-second timer. Upon completion, you gain 30% - 80% (based on level) attack speed as well as removing the attack speed cap for 3 seconds. Attacking a champion while the effect is active will extend the duration to 6 seconds. Cooldown: 6 seconds
Problem: Lethal tempo takes 1.5 seconds to proc and 6-second cooldown, a long time to stay unimpactful in a team fight. Has a weak laning phase, suffer much from a proc bot lane composition, like Sona + Ezreal. Low survivability compares to Fleet footwork. In a professional team fights, they can very easily bait out lethal tempo and actually starts a team fight when it is on cooldown.
Solution 1 (my favorite) : lethal tempo: PASSIVE: No attack speed cap. Each damage (aoe damage will count as one) on a champion will give 8% - 20% (base on level) attack speed for 6 seconds, duration refresh upon killing a champion. (attack speed reduce gradually if the effect ends). Cooldown: 2 seconds
reflection: This version of lethal tempo remove a lot of burst damage, as we need now need to attack (auto attack & ability) 6 times on a champion to gain the same buff (30% - 80% attack speed) as the old lethal tempo do. However, since the attack speed is uncapped all the time, and cool down is only 2 seconds, players have more choice on when they want to go in, and it's harder for the opposite team to punish them for proc lethal tempo. The laning phase will be better if the trading duration is more than one auto attack since they can get potentially one more auto attack than players with fleet footwork.
solution 2: lethal tempo: PASSIVE: Damaging an enemy champion begins a 1.5-second timer. Upon completion, lethal tempo went to cool down, you gain 30% - 80% (based on level) attack speed as well as removing the attack speed cap for 3 seconds. Each attack will **_reduce the cooldown by 1 second. Cooldown: 9 seconds
reflection: This basically is the old version of lethal tempo, however, it's not punished as hard during landing phase since they can reduce cooldown by attacking. In an ideal situation (where someone can continuously attack), the cooldown will basically be zero at 2.00 attack speed. in a team fight, it still contains that huge burst and it is still baitable but if there are minions then this version is much stronger than the old version.
solution 3: lethal tempo: PASSIVE: dealing 30% of a champion's current health in 2 seconds or loss 30% of current health in 2 seconds will gain 50% - 100% (based on level) attack speed. Attack speed cap is always removed (even during cooldown). cooldown: 6 seconds.
reflection:
So, lethal tempo only procs when it is the real deal. This will let players proc as much as they want and do not worry about lethal tempo went on cooldown and get punished. In a team fight, it's harder to proc because dealing 30% of the health of a tank ( (I assume people take this will build damage, not a tank, and not an assassin. WAIT! OH SHIT MASTER YI), in team fight is very hard in 2 seconds, and as a squishy reduce 30% of the health for the effect is extremely dangerous. So this is a "lethal tempo" for both the enemy and you.
Hopefully, this can help.