I hear alot of people complain about AP Ez mid after the runeglaive patch. But runeglaive is not the problem here. Runeglaive only gave Ezreal waveclear. The problem is actually in Luden's Echo coupled with Ezreals ABSURDLY high base damages and high AP ratios.
Let's assess this.
Q: Low CD spell that reduces the CD of his other spells when it hits. This also procs on hit effects AND has an ap ratio of 0.4 coupled with around 240 base. So, just still spell alone, will proc runeglaive/lich bane, will deal even more damage with the AP ratio and reduces the CD on other spells. Got that?
W: 250 BASE damage and 0.8 ap ratio. 9 sec base cooldown. Only hits champions, so It can't be blocked by minions. This is insane damage coupled with a low cooldown (because every ezreal builds some cdr) that can hit multiple champions at once. Q also reduces the already low CD even further.
E: 275 EFFING BASE DAMAGE with 0.75 ap ratio. Doesn't need to be targeted, also couple with a blink. 11 second cd, reduced by Q again. This base damage in tandem with the blink is too much.
R: 650 EFFIN BASE DAMAGE with 0.9 ap ratio. Global range. 80 second cd, reduced by Q ofcourse. This is the ability that you see ezreal almost one shot AD carries with in late game. The 0.9 ap ratio on a spell like this is absurd. Even though the damage is reduced each time it hit's a target, the total damage this spell can do is INSANE. Ezreal will have this ability up every team fight. 100% guaranteed.
So, let's assume it's late game, ezreal has let's say 700 AP and has luden's echo + runeglaive. Let's calculate the damage of his combo.
Q 730 damage(glaive included), some physical, mostly magic.
W 810 magic damage.
E 800 magic damage.
R 1280 magic damage.
Luden's Echo 170 magic damage.
That's 3790 damage. This is the problem here. This kind of damage and the SAFETY of it. Extremely low cooldowns for everything, high base damages and ap ratios for everything. Extra damage from glaive and echo. A fed Ezreal will kill an AD carry with couple of his spells. His ult alone halves the enemy carries HP bars.
Ezreal is an extremely safe champion, with insane damage potential. He has always been like this. Runeglaive only gave him wave clear. The damage radius on runeglaive is not big enough to make any real difference. Ezreal is now easier to play in mid lane because of runeglaive. His damage was always like this.
So, like I said, runeglaive is NOT the problem with AP Ez. It only made it a bit easier to farm with him. The insane damage with low cooldowns was always there and Luden's echo is one the worst offenders in this.
AP Ez needs nerfs. Runeglaive made it easy to abuse his OP damage and safety. The item itself is fine.