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Cassiopeia Build Guide by RezoneVerified

Middle 💀 [ 14.12 NEW SEASON 14] CASSIOPEIA - The POISON Queen of Midlane ☠ 💀

Middle 💀 [ 14.12 NEW SEASON 14] CASSIOPEIA - The POISON Queen of Midlane ☠ 💀

Updated on June 14, 2024
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League of Legends Build Guide Author RezoneVerified Build Guide By RezoneVerified 531 30 1,535,141 Views 19 Comments
531 30 1,535,141 Views 19 Comments League of Legends Build Guide Author RezoneVerified Cassiopeia Build Guide By RezoneVerified Updated on June 14, 2024
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Runes: Conqueror

1 2
Presence of Mind
Legend: Tenacity
Coup de Grace


+9 Adaptive (5.4 AD or 9 AP)
+9 Adaptive (5.4 AD or 9 AP)
+10% Tenacity/Slow Resist


1 2
LoL Summoner Spell: Flash


LoL Summoner Spell: Ignite


Threats & Synergies

Threats Synergies
Extreme Major Even Minor Tiny
Show All
None Low Ok Strong Ideal
Extreme Threats
Ideal Synergies
Ideal Strong Ok Low None

How is it going guys! My name is Rezone and I'm a Master Tier Midlane main. I peaked at 270 LP Master Tier this Season and have 4.5 Million Mastery Points on Heimerdinger! I upload gameplays, guides, tips and pretty much any other League of Legends related content you could ever ask for!

I was the BEST HEIMERDINGER EUW in Season 7 and I'm best known for inventing the Holy Trinity of Tilt build on Heimerdinger a couple of seasons ago (Banner of Command, ZZ'Rot Portal and Rylai's)! I've also recently competed in TWITCH RIVALS where I played Heimerdinger ADC and came joint first against other streamers such as TFBlade.

Cassiopeia is always a strong, midlane pick and can be safely blindpicked into the majority of champions and comps. She has very strong outplay potential, but is skillshot reliant and has a medium learning curve. She's very rewarding to play, and her kit feels extremely smooth. You will thank yourself for learning Cassiopeia, and find yourself being able to climb easily once you do.

Flash is the best summoner spell in the game, it is your escape tool and engage tool. It can also help you get in the perfect position for a clutch ultimate.

Ignite is extremely powerful on Cassiopeia, providing her with extra kill pressure, and another burn like Liandry's Torment, along with her poison. It also offers Grievous Wounds, which is very useful against champions with high healing, such as Vladimir and Akali.

Teleport is important for being able to teleport back to lane after recalling, and for being able to help out your team in difficult spots, turning a 3v2 into a 3v3 and potentially turning the fight. It's very good vs roaming champions such as Twisted Fate, Aurelion Sol, Zed etc.
Conqueror Conqueror is so strong currently, even after the nerfs on ranged champions. You gain 2-5 adaptive focus per stack, and when fully stacked (12 stacks), you heal for 6% of all damage dealt to champions. This increases our sustain substantially and is one of the best runes currently, especially with the AoE damage Cassiopeia does.

Presence of Mind Presence of Mind is essential for Cassiopeia, as everytime you gain a takedown, you restore 15% of your maximum mana, and damaging an enemy champion increases your mana regen by up to 11 per second, reduced to 80% for ranged. Cassiopeia has very spammable spells (hello carpal tunnel!), and this extra mana is invaluable to keeping her in fights longer.

Legend: Haste Legend: Haste is the perfect rune to choose, it works well on any champion but with Cassio it complements her kit and build well.

Coup de Grace Coup de Grace adds that little bit extra damage that all poke mages enjoy. It increases the damage you deal to targets below 40% hp, which is fantastic for our burns.

Overgrowth Overgrowth is fantastic scaling into late game and allows you to survive alot of end game burst due to increased health.

Conditioning Conditioning is a great pick combing well with conqueror and allowing you to sustain well in lane.


Seraph's Embrace
Your core item on Cassiopeia, as to deal damage, she needs to be spamming her abilities, and this helps us to sustain our mana during laning phase and into the mid/late game. Once we have stacked our Archangel's Staff, it transforms into Seraph's Embrace, which provides us with ability power equal to 2% maximum mana. This also offers a shield that procs when we are reduced below 30% max health, this is fantastic as it procs by itself.


Rylai's Crystal Scepter
Another core item for Cassiopeia is Rylai's, providing us with a slow for every ability we use - and proccing on our burns/poison, permanently keeping the enemy slowed and allowing us to catch up with them! With the new item overhaul, this increases our AP significantly and gives us a bit more durability with 400 hp.


Zhonya's Hourglass
With Zhonya's Hourglass, we gain the ability to negate all damage for 2.5s - including damage from Ignite and Death Mark. Invaluable on a squishy mage like Orianna, and even better when you're vs assassins.


Rabadon's Deathcap
Increasing our overall ability power by 35%, while providing an extra 120AP. This item increases your burst exponentially, and despite the hefty price tag, is more than worth it if you're ahead or need some insane burst.


This item is fantastic vs healers such as Vladimir, Soraka, Yuumi etc. It provides us with grievous wounds, negating healing by 40%, - it also provides a nice chunk of AP for us.


Void Staff
If the enemy team is tanky, or building a lot of magic resist, Void Staff can help penetrate that with an extra 40% mpen - absolutely fantastic to get through that annoying magic resist.



Mejai's Soulstealer
If you're ahead in lane and decide to purchase Dark Seal, this is the next upgrade, allowing you to proceed to 25 stacks. Fantastic item if you're ahead and want to continue your lead and close out the game fast. If you're at risk of dying, you lose 10 stacks, as opposed to the 4 on Dark Seal, so take heed on splashing out for this item.


Banshee's Veil
This item is like Zhonya's Hourglass, but it negates only one spell every 40s - after taking no damage from champions. It's great for long range engage champions such as Blitzcrank and Alistar, allowing you to not get caught out by hidden hooks or headbutts.


Liandry's Torment
The best choice as a 3rd buy...whats better than poison? FIREY POISN, dealing damage with abilities causes the enemies to burn 1% maximum health magic damage per second for 3 seconds,.. This absolutely shreds down enemies and tanks, and synergises well with Cassiopeia's poison.

Rod of Ages

Rod of Ages
Rod on Cassio can work well if you are wanting to scale into the late game, this combined with Liandries and Seraphs, you become tanky with a huge mana pool. Rod of Ages can work with Rylai's Crystal Scepter at the core as it allows Cassio to kite and spam her Serpent's Fang. This play style can also work for toplane as the tankiness from Rod allows you to scale into toplaner and survive a lot of mid game pressure or all in.

Serpentine Grace (Passive)
Cassiopeia cannot purchase boots and instead gains 4 − 72 (based on level) base movement speed, for a total of 332 − 400 (based on level) movement speed.
  • The movement speed from Serpentine Grace is worth 48 gold per level, up to a maximum of 864 gold at level 18.

Noxious Blast (Q)

COST: 50 / 60 / 70 / 80 / 90 mana
After a 0.4-second delay, Cassiopeia blasts the target area with Noxious Poison, dealing magic damage every second for 3 seconds to all enemies it hits.

Cassiopeia gains bonus movement speed that decays over 3 seconds if Noxious Blast hits an enemy champion.
  • Noxious Blast uses quick casting by default.
  • Bonus Movement Speed: 30 / 35 / 40 / 45 / 50%

Miasma (Q)

COST: 70 / 80 / 90 / 100 / 110
COOLDOWN: 24 / 22 / 20 / 18 / 16s
Cassiopeia spits forth eight bolts of venom in an arc, leaving toxic clouds of Debilitating Poison where they hit the ground for 5 seconds.

Debilitating Poison deals magic damage to enemies standing upon it every second, also grounding them and applying a slow that decays over the area's duration.

Twin Fang (Q)

RANGE: 700
COST: 50 mana
Cassiopeia launches her fangs at the target enemy, dealing 52 − 120 (based on level) (+ 10% AP) magic damage. If Twin Fang kills its target, or the target is killed mid-flight, its mana cost is refunded.

If the target is poisoned, Twin Fang deals bonus magic damage and heals Cassiopeia. The heal is only 25% as effective against minions and small monsters.

Petrifying Gaze (Q)

ANGLE: 80°
COST: 100 mana
COOLDOWN: 120 / 100 / 80
After a brief delay, Cassiopeia blasts enemies in a cone in the target direction, dealing magic damage to all enemies hit.

Enemies facing Cassiopeia are stunned for 2 seconds upon being hit by Petrifying Gaze, and all other affected enemies are instead slowed by 40% for the same duration.

  • Petrifying Gaze's target direction will change if Cassiopeia's facing direction changes during the cast time (i.e. through knockbacks).
  • The facing direction of champions whose abilities/animations cause them to lock their facing or spin is always the direction they are moving in. For abilities that cause the champion to spin in place (e.g. Death Lotus) it will factor the direction they were facing on cast.

Early - Mid Game

During laning phase, you want to trade efficiently with your enemy, avoiding extended trades due to Cassiopeia's low base mana pool. You can easily use Noxious Blast on the enemy when they walk up for CS, as they must stand still for a split second to AA. Before you get Tear of the Goddess (if you chose to start with Doran's Ring or Corrupting Potion, you want to use your mana sparingly. You can use Twin Fang to last hit minions, and farm towards your tear. You should use proper wave management by freezing the wave near your tower, so you're not at risk of being ganked, and make sure to put a ward nearby. Cassiopeia is immobile, so be wary of using your Flash, as you have no surefire escape after - she is an easy target to gank.

Cassiopeia has good push potential, and roam potential. You should push when optimal and look to gank other lanes - you can even gank normally ungankable lanes such as Ezreal as your Miasma grounds the enemy, rendering their dashes or blinks useless.

When you get Tear of the Goddess, you want to be stacking it as quickly as possible, last hitting with Twin Fang, and trading aggressively with the enemy. Conqueror is very strong on Cassiopeia as she can stack it very fast with her low cooldowns. This provides us with a large chunk of AP and also heals us for 8% of all damage dealt to champions, meaning we can easily stay sustained during prolonged trades.

Mid - Late Game

During this point, our Archangel's Staff should be transformed into Seraph's Embrace, and we generally have an unlimited mana pool. If you've been CSing correctly, or getting kills, you should have Rylai's Crystal Scepter, which slows the enemy on all your abilities - basically a permaslow for Cassiopeia, and you can look to play aggressively. Cassiopeia's damage is generally unmatched during mid game, she can shred through targets with ease, and keeping them slowed and grounded while she runs (slithers?) them down.

Focus on helping out with objectives as much as possible, you can shred through the Dragons, and the changes to them in Season 10 make them all the more important and impactful.

Cassiopeia has an extremely strong late game, she can tear through any single target with unmatched speed, and has the capability to have a full, 6 item damage build due to not needing to buy boots. Cassiopeia wants to be with her team and set up big teamfight ultimate's, especially if the enemy decides to facecheck a brush while you're hiding as 5. This will guarantee you a stun off Petrifying Gaze and can in turn win you the game. Make sure to keep Miasma on the ground, locking enemies down and finding ample opportunities to use your ultimate. Even the slow is useful, so don't hold it to find that picture perfect, YouTube worthy 5man stun!
Thanks for reading my Cassiopeia guide and I really hope you can take some of this information and apply it to your ranked games! Please drop me a comment, and let me know if there's anything I can improve on. I hope you can pop by any of my social media's and say hi! Feel free to check out any of my other midlane champion guides, and I hope you enjoy them just as much.

  • 29/12/2019 - Published Guide.
  • 17/11/2020 - Updated for preseason.
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League of Legends Build Guide Author RezoneVerified
RezoneVerified Cassiopeia Guide
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💀 [ 14.12 NEW SEASON 14] CASSIOPEIA - The POISON Queen of Midlane ☠ 💀

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