Does lethality work on Zeri? : yes
and works with lethality so all you have to do is spam and and + for finish .

Is lethality zeri good? : Yes I can't say it's op or better than crit zeri but its really funny and good build

Pros:
1- High burst dmg
2- Good mid game
3- Easy waveclear with W
4- Good vs squiashies
5- Good poke
6- Easy to steal objectives
7- Good roam

Cons :
1- Bad vs Tanks
2- Bad vs Mobility Champions
3- Low attack speed
4- Squishy
5- Hard to master
6- Bad Early game
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Zeri

Zeri Early game Is Weak [1-10Mins]
Zeri Mid game Is Strong [10-20Mins]
Zeri Late game Is Average [+20Mins]

Zeri's attacks are treated as abilities instead of attacks and can be charged up by moving and casting Burst Fire. Uncharged attacks consume a small amount of charge deal 10-25 (+3% of ability power) magic damage and execute enemies below 60−150 (+18% of ability power) health (depending on level). A fully charged attack deals 90−200 (+110% of ability power) (+1−15% of target's maximum health) magic damage and consumes all charge (depending on level).

Zeri fires a burst of 7 rounds that deals 15 / 17 / 19 / 21 / 23 (+1.04 / 1.08 / 1.12 / 1.16 / 1.2% of attack damage) physical damage to the first enemy hit. This ability is treated as an attack.

Cooldown: 1 / Zeri's attack speed

Zeri fires an electric pulse that deals 20 / 60 / 100 / 140 / 180 (+25% of ability power) (+1.3 per attack damage) magic damage and slows the first enemy hit by 30 / 35 / 40 / 45 / 50% for 2 seconds.

If the pulse hits terrain, it expands into a laser that applies the effects in an area and critically strikes champions and monsters.

(Tips)
Zeri cast time scale down with attack speed

Zeri dashes a short distance and vaults over any terrain she touches, greatly extending the dash range. For the next 5 seconds, her shots of Burst Fire pierce dealing 0-85% (depending on critical strike chance) damage to enemies after the first and an additional 20 / 22 / 24 / 26 / 28 (+20% of ability power) (+0.12 per bonus attack damage) magic damage on-hit to the first target struck.

Hitting an enemy champion with an attack or ability reduces this ability's cooldown by 0.5 seconds. Critical strikes reduce the cooldown by 1.5 seconds instead.

Zeri discharges a nova of electricity, dealing 175 / 275 / 375 (+110% of ability power) (+0.85 per bonus attack damage) magic damage to nearby enemies. If she hits an enemy champion, Zeri gains 30% attack speed and 10% movement speed for 5 seconds. Hitting an enemy champion with an attack or ability extends this ability's duration and adds a stack of Overcharge for 1.5 seconds. Critical strikes add 2 additional stacks. Each stack grants 0.5% movement speed.

During this time, Burst Fire becomes a faster triple shot that chains 25% AD physical damage to nearby enemies. This damage can critically strike.