League of Legends Cassiopeia Guide: Best Build, Runes & Combos

Cassiopeia is a deadly mid lane mage in League of Legends known for her high DPS, strong lane control, and powerful scaling. With her ability to melt enemies using Twin Fang and lock them down with Miasma and her ultimate, Cassiopeia thrives in extended fights and tight skirmishes. Unlike most champions, she can’t buy boots, but makes up for it with insane late-game power and consistent damage output. In this guide, we’ll break down the best build, runes, items, and combos so you can master the Serpent’s Embrace and carry games with her poisonous burst.

Cassiopeia Abilities Overview in League of Legends

Passive – Serpentine Grace
Cassiopeia gains movement speed per level but cannot buy boots. This allows her to scale into a fast, slippery mage without spending gold on mobility items.

Q – Noxious Blast
Cassiopeia blasts a targeted area with poison, dealing magic damage over time and granting her bonus movement speed if she hits an enemy. It’s great for poking, kiting, and setting up her other abilities.

W – Miasma
Cassiopeia spreads a large cloud of poison that grounds and slows enemies, preventing them from using movement abilities like dashes or flashes. This is a powerful zoning and anti-mobility tool in fights.

E – Twin Fang
Her main source of damage. Cassiopeia rapidly fires fangs at poisoned targets, dealing bonus magic damage and healing her slightly if the target is poisoned. The cooldown is nearly instant when used correctly, making it her DPS engine.

R – Petrifying Gaze
Cassiopeia fires a cone in front of her. Enemies facing her are stunned, while enemies with their backs turned are slowed. It’s a game-changing ability that punishes poor positioning and can turn teamfights instantly.

Together, Cassiopeia’s kit makes her a sustained damage powerhouse who controls space, punishes missteps, and dominates late-game fights with precision and timing.

How To Play Cassiopeia In League of Legends

Best Summoner Spells For Cassiopeia

The best summoner spells for Cassiopeia are Flash and Teleport. Flash is essential for repositioning, escaping danger, or making aggressive plays with your ultimate. Teleport gives you great map control, letting you return to lane quickly or assist in side lane skirmishes. If you’re looking for more kill pressure in lane, Ignite is also a strong option—especially against healing champs. But overall, Flash + Teleport is the most reliable setup for scaling and consistent impact throughout the game.

Best Runes for Cassiopeia

The best runes for Cassiopeia come from the Precision tree for sustained damage and mana efficiency. Start with Conqueror as your keystone to stack bonus damage and healing during extended trades. Follow with Presence of Mind for mana regeneration on takedowns, Legend: Tenacity to reduce crowd control, and Last Stand for more damage when low on health. For your secondary tree, go Domination with Taste of Blood for lane sustain and Treasure Hunter or Ultimate Hunter for snowballing or more frequent ult usage. Take Attack Speed, Adaptive Force, and Magic Resist or Armor depending on your lane opponent. This rune setup helps Cassiopeia stay aggressive in lane, sustain through fights, and scale into a late-game monster.

Best Build For Cassiopeia

The best build for Cassiopeia in League of Legends focuses on consistent DPS, mana sustain, and survivability in extended fights. Start with Tear of the Goddess and build into Archangel’s Staff early for mana and AP scaling. Then go for Liandry’s Torment as your mythic to shred tanks and deal burn damage in long fights. Rylai’s Crystal Scepter is a great follow-up for the slow, making it easier to land your Twin Fangs. After that, build Zhonya’s Hourglass for survivability and Void Staff to cut through magic resist. Finish with Rabadon’s Deathcap for a huge AP power spike. This build makes Cassiopeia tanky, sustained, and a serious threat in both teamfights and 1v1s.

Best Combos To Learn For Cassiopeia

The best combos to learn for Cassiopeia focus on poisoning enemies and spamming E – Twin Fang for maximum damage. A basic trading combo is Q → E spam, where you land Noxious Blast to apply poison and immediately follow with rapid Twin Fang casts. For zoning or stopping mobile champs, use W → Q → E spam, placing Miasma first to ground enemies, then land your Q and unload your E. In all-ins or teamfights, the ideal engage combo is R → W → Q → E spam — use Petrifying Gaze to stun enemies, drop Miasma to keep them in place, hit Noxious Blast, then spam Twin Fang for huge damage. Always remember: poison must land before spamming E, and well-timed R stuns can completely swing fights in your favor.

Conclusion

Cassiopeia is a powerful scaling mage who thrives in extended fights and rewards precision and smart positioning. With the right runes, items, and combo execution, she can dominate mid lane, control teamfights, and melt even the tankiest enemies. Mastering her poison mechanics and timing your abilities correctly will turn you into a constant threat from early lane phase to late-game carries.